ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (136)
  • 73.20.Dx  (74)
  • stability  (62)
  • Springer  (136)
  • American Geophysical Union
  • American Institute of Physics (AIP)
  • American Physical Society
  • Blackwell Publishing Ltd
  • Nature Publishing Group
  • 2000-2004  (24)
  • 1995-1999  (112)
  • 1945-1949
  • Physics  (136)
Collection
  • Articles  (136)
Publisher
  • Springer  (136)
  • American Geophysical Union
  • American Institute of Physics (AIP)
  • American Physical Society
  • Blackwell Publishing Ltd
  • +
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 74 (1999), S. 19-57 
    ISSN: 1572-9478
    Keywords: stability ; Hamiltonian ; two centers ; oblate planet ; galactic disks ; dipole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Relative equilibria occur in a wide variety of physical applications, including celestial mechanics, particle accelerators, plasma physics, and atomic physics. We derive sufficient conditions for Lyapunov stability of circular orbits in arbitrary axisymmetric gravitational (electrostatic) and magnetic fields, including the effects of local mass (charge) and current density. Particularly simple stability conditions are derived for source‐free regions, where the gravitational field is harmonic (∇2U = 0) or the magnetic field irrotational (∇ × B = 0). In either case the resulting stability conditions can be expressed geometrically (coordinate‐free) in terms of dimensionless stability indices. Stability bounds are calculated for several examples, including the problem of two fixed centers, the J2 planetary model, galactic disks, and a toroidal quadrupole magnetic field.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 75 (1999), S. 251-285 
    ISSN: 1572-9478
    Keywords: unrestricted problem ; rotational motion ; rigid body dynamics ; libration points ; stability ; resonances
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present an analysis of the model introduced by Kokoriev and Kirpichnikov (1988) for the study of unrestricted planar motion of a point mass and a symmetric rigid body whose gravity field is approximated by two point masses (a dumb-bell model). To show possible generalization of the model, we give a systematic derivation of equations of motion for a more general unrestricted problem of a point and a rigid body possessing a plane of dynamical symmetry. We give a simple description of bifurcation of triangular libration points, and we perform an analysis of their linear stability. We propose to extend the model of Kokoriev and Kirpichnikov (1988) to a case when the symmetric body is oblate. In the proposed model the gravity field of moving and rotating body is approximated by two complex masses at complex distance (a complex dumb-bell model). An analysis of bifurcation of the triangular libration points in this model is also presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 78 (2000), S. 227-241 
    ISSN: 1572-9478
    Keywords: stability ; normal form ; spin-orbit resonance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We consider a model of spin-orbit interaction, describing the motion of an oblate satellite rotating about an internal spin-axis and orbiting about a central planet. The resulting second order differential equation depends upon the parameters provided by the equatorial oblateness of the satellite and its orbital eccentricity. Normal form transformations around the main spin-orbit resonances are carried out explicitly. As an outcome, one can compute some invariants; the fact that these quantities are not identically zero is a necessary condition to prove the existence of nearby periodic orbits (Birkhoff fixed point theorem). Moreover, the nonvanishing of the invariants provides also the stability of the spin-orbit resonances, since it guarantees the existence of invariant curves surrounding the periodic orbit.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 63 (1995), S. 205-225 
    ISSN: 1572-9478
    Keywords: Restricted three body problem ; Lagrangian points ; resonances ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The problem of stability of the Lagrangian pointL 4 in the circular restricted problem of three bodies is investigated close to the 1 : 2 commensurability of the long and short period libration. By stability we define boundedness of the solution for a given initial finite displacement from the equilibrium point as function of the mass parameter μ close to the commensurability. A rigorous treatment close to the resonance condition is possible using a transformation that diagonalizes the matrix related to the linear part of the equations of motion. The so obtained equations are further transformed to action angle type variables. Then using an isolated resonance approach, only the slowly varying terms are kept in the equations and two independent isolating first integrals can be found. These integrals finally enable us to solve the stability problem in an exact way. The so obtained results are compared to numeric integration of the equations of motion and are found to be in perfect agreement.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 61 (1995), S. 181-196 
    ISSN: 1572-9478
    Keywords: Periodic solutions ; stability ; restricted three-body problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The periodic solutions of the restricted three-body problem representing analytic continuations of Keplerian rectilinear periodic motions are well known (Kurcheeva, 1973). Here the stability of these solutions are examined by applying Poncaré's characteristic equation for periodic solutions. It is found that the isoperiodic solutions are stable and all other solutions are unstable.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 67 (1997), S. 181-204 
    ISSN: 1572-9478
    Keywords: Hamiltonian systems ; symplectic mappings ; normal forms ; resonances ; stability ; three degrees of freedom
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We analyze four-dimensional symplectic mappings in the neighbourhood of an elliptic fixed point whose eigenvalues are close to satisfy a third-order resonance. Using the perturbative tools of resonant normal forms, the geometry of the orbits and the existence of elliptic or hyperbolic one-dimensional tori (fixed lines) is worked out. This allows one to give an analytical estimate of the stability domain when the resonance is unstable. A comparison with numerical results for the four-dimensional Hénon mapping is given.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 61 (1995), S. 1-19 
    ISSN: 1572-9478
    Keywords: Three body problem ; stability ; surface of section ; commensurability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The model of the circular restricted problem of three bodies is used to investigate the sensitivity of the third body motion when it is given a positional or velocity deviation away from the L4 triangular libration point. The x-axis is used as a criteria for defining the stability of the third body motion. Poincaré's surfaces of section are used to compare the regions of periodic, quasi-periodic and stochastic motion to the trajectories found using the definition of stability (not crossing the x-axis) defined in this study. Values of the primary/secondary mass ratios (μ) ranging from 0 to the linear critical value 0.038521... are investigated. Using this new form of stability measure, it is determined that certain values of μ are more stable than others. The results of this study are compared, and found, to give agreeable results to other studies which investigate commensurabilities of the long and short period terms of periodic orbits.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 61 (1995), S. 261-285 
    ISSN: 1572-9478
    Keywords: galactic dynamics ; periodic orbits ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study the stability of axial orbits in analytical galactic potentials as a function of the energy of the orbit and the ellipticity of the potential. The problem is solved by an analytical method, the validity of which is not limited to small amplitudes. The lines of neutral stability divide the parameter space in regions corresponding to different organizations of the main families of orbits in the symmetry planes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 66 (1996), S. 191-202 
    ISSN: 1572-9478
    Keywords: resonance ; restricted problem ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The stability of triangular libration points, when the bigger primary is a source of radiation and the smaller primary is an oblate spheroid. has been investigated in the resonance cases ω1 = 2ω2 and ω1 = 3ω2. The motion is unstable for all the values of parameters q and A when ω1 = 2ω2 and the motion is unstable and stable depending upon the values of the parameters q and A when ω1 = 3ω2. Here q is the radiation parameter and A is the oblateness parameter.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 69 (1997), S. 271-281 
    ISSN: 1572-9478
    Keywords: restricted three-body problem ; libration points ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The existence and stability of triangular libration points in the relativistic restricted three-body problem has been studied. It is found that L4,5 are unstable in the whole range 0 ≤ µ ≤ 1/2 in contrast to the classical restricted three-body problem where they are stable for 0 〈 µ 〈 µ0, where µ is the mass parameter and µ0 = 0.03852....
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 69 (1997), S. 317-330 
    ISSN: 1572-9478
    Keywords: artificial satellite ; Nekhoroshev's theory ; normal form ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We investigate the significance of long time stabilty predictions in the light of Nekhoroshev's theory by studying the orbits of artificial satellites. As a simplified model problem we consider the so-called J2problem for an earth's satellite, neglecting luni-solar perturbations and nonconservative effects. We consider a wide range of orbits, excluding those which are too close to the critical inclination. Most of the orbits turn out to be stable for times larger than the estimated age of the solar system, thus proving that, as far as dissipation can be neglected, stability in Nekhoroshev's sense may be effective for physically realistic systems.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Celestial mechanics and dynamical astronomy 70 (1998), S. 41-58 
    ISSN: 1572-9478
    Keywords: three-body problem ; libration points ; stability ; normal forms.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper we consider the problem of motion of an infinitesimal point mass in the gravity field of an uniformly rotating dumb-bell. The aim of our study is to investigate Liapunov stability of Lagrangian libration points of this problem. We analyze the stability of libration points in the whole range of parameters ω, μ of the problem. In particular, we consider all resonance cases when the order of resonance is not greater than five.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Optical review 6 (1999), S. 28-36 
    ISSN: 1349-9432
    Keywords: optical propagation equation ; stability ; picosecond pulse ; 3-dimensional computation ; Fresnel’s distribution ; fast Fourier transform
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a new simulation code able to simulate the entire propagation of laser pulse, from the amplifiers level up to the focusing stage. This algorithm has some new characteristics that we intend to present. It computes the three-dimensional optical propagation equation using no approximation other than its picosecond expression. The stability has been carefully studied so that it can be applied to any geometry. This is a great improvement since, up to now only cylindrical geometry was accessible for accuracy. In this paper we also present a method using Fast Fourier Transform able to evaluate with a high accuracy, Fresnel’s distribution of a focused laser pulse. The advantages provided by our algorithm are its rapidity and its high physical understanding of the focusing phenomena.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für angewandte Mathematik und Physik 47 (1996), S. 809-816 
    ISSN: 1420-9039
    Keywords: 34D20 ; 34D35 ; 35Q72 ; 73H10 ; 73K03 ; Elastic string ; stability ; energy-momentum ; axial motion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We establish the stability of axial motions (steady motions along the lengthwise direction) of nonlinearly elastic loops of string. A key observation here is that a linear combination of the total energy and the total circulation of the string, both of which are conserved quantities, yields an appropriate Liapunov function. From our previous work [5], we know that there are uncountably many shapes corresponding to a given axial speed. Accordingly, we establish “orbitai” stability (modulo this collection of relative equilibria). For a well-defined class of “soft” materials, there is an upper bound on the axial speed sufficient for stability; “stiff” materials are shown to be orbitally stable at any axial speed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    ISSN: 1432-0649
    Keywords: 78.47.+p ; 73.20.Dx ; 71.35,+z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We use femtosecond time-resolved transmission spectroscopy to study the density and time dependence of transient absorption changes of CdSe nanocrystals. Our data show pronounced absorption saturation up to complete bleaching of the lowest optical transition. At high carrier density the nonlinear spectra show several peaks that can be related to the two lowest quantized electron states. Thetime dependence of the carrier-induced absorption changes indicates an ultrafast relaxation process within the strongly broadened absorption lines.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Letters in mathematical physics 53 (2000), S. 313-320 
    ISSN: 1573-0530
    Keywords: partial differential equations ; nonlinearities ; symmetries ; stability ; minimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We suggest a simple but general method of establishing symmetry properties of stable solutions of nonlinear elliptic equations. The method relies on characterization of symmetry breaking with a help of zero modes and on a generalization of the Perron–Frobenius theory.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 88 (1997), S. 691-711 
    ISSN: 1572-9613
    Keywords: Quasicrystals ; nonperiodic tilings ; classical lattice-gas models ; ground states ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We give strong evidence that noncrystalline materials such as quasicrystals or incommensurate solids are not exceptions, but rather are generic in some regions of phase space. We show this by constructing classical lattice-gas models with translation-invariant finite-range interactions and with a unique quasiperiodic ground state which is stable against small perturbations of two-body potentials. More generally, we provide a criterion for stability of nonperiodic ground states.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 91 (1998), S. 285-305 
    ISSN: 1572-9613
    Keywords: Chapman–Enskog expansion ; Burnett equation ; Boltzmann equation ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper continues the author's study of procedures for rewriting the well-known Chapman–Enskog expansion used in the kinetic theory of gases. The usual Chapman–Enskog expansion, when used in isothermal fluid motion, will introduce nonlinear instability at super-Burnett order O(ε3) truncation. The procedure given here eliminates the truncation instability and produces the desired dissipation inequality.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 95 (1999), S. 835-850 
    ISSN: 1572-9613
    Keywords: quasicrystals ; nonperiodic tilings ; classical lattice-gas models ; nonperiodic ground states ; nonperiodic Gibbs states ; stability ; frustration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract One of the fundamental problems of quasicrystals is to understand their occurrence in microscopic models of interacting particles. We review here recent attempts to construct stable quasicrystalline phases. In particular, we compare two recently constructed classical lattice-gas models with translation-invariant interactions and without periodic ground-state configurations. The models are based on nonperiodic tilings of the plane by square-like tiles. In the first model, all interactions can be minimized simultaneously. The second model is frustrated; its nonperiodic ground state can arise only by the minimization of the energy of competing interactions. We put forward some hypotheses concerning stabilities of nonperiodic ground states. In particular, we introduce two criteria, the so-called strict boundary conditions, and prove their equivalence to the zero-temperature stability of ground states against small perturbations of potentials of interacting particles. We discuss the relevance of these conditions for the low-temperature stability, i.e., for the existence of thermodynamically stable nonperiodic equilibrium states.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 95 (1999), S. 867-902 
    ISSN: 1572-9613
    Keywords: kinetics of phase transitions ; domain coarsening ; asymptotic behavior ; self-similarity ; stability ; chaos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The classical Lifshitz–Slyozov–Wagner theory of domain coarsening predicts asymptotically self-similar behavior for the size distribution of a dilute system of particles that evolve by diffusional mass transfer with a common mean field. Here we consider the long-time behavior of measure-valued solutions for systems in which particle size is uniformly bounded, i.e., for initial measures of compact support. We prove that the long-time behavior of the size distribution depends sensitively on the initial distribution of the largest particles in the system. Convergence to the classically predicted smooth similarity solution is impossible if the initial distribution function is comparable to any finite power of distance to the end of the support. We give a necessary criterion for convergence to other self-similar solutions, and conditional stability theorems for some such solutions. For a dense set of initial data, convergence to any self-similar solution is impossible.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 101 (2000), S. 731-746 
    ISSN: 1572-9613
    Keywords: attractive Bose–Einstein condensates ; nonlinear Schrödinger equation ; stability ; ground state ; variational arguments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We propose the critical nonlinear Schrödinger equation with a harmonic potential as a model of attractive Bose–Einstein condensates. By an elaborate mathematical analysis we show that a sharp stability threshold exists with respect to the number of condensate particles. The value of the threshold agrees with the existing experimental data. Moreover with this threshold we prove that a ground state of the condensate exists and is orbital stable. We also evaluate the minimum of the condensate energy.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 61 (1995), S. 467-474 
    ISSN: 1432-0630
    Keywords: 73.20.-r ; 73.20.Dx ; 61.16.Ch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract It is shown how wire structures a few nanometers wide can be fabricated by decorating step edges at vicinal surfaces. Their growth modes and electronic states are studied using Scanning Tunneling Microscopy (STM) and inverse photoemission. The observed growth modes are two-dimensional analogs of Stranski-Krastanov growth and layer-by-layer growth in three dimensions, e.g., for Cu on stepped Mo(1 1 0) and W(1 1 0), respectively. Contrast between different metals is achieved in STM pictures by resonant tunneling via surface states and image states, with the latter providing a map of the work function. The limit of single atomic rows decorating step edges is studied by inverse photoemission, and an energy shift of 0.4 eV is found for electronic states of step atoms. We expect stripe structures to become useful for the study of two- vs one-dimensional magnetism, for magnetoresistive films, and in the design of anisotropic materials.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    ISSN: 1432-0630
    Keywords: 73.20.Dx ; 13.40. DK
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Analytical expressions for the transmission coefficient and the resonance condition in unsymmetrical rectangular double-barrier structures are derived theoretically by taking into account the mass difference between well and barrier layers. It is found that resonant tunneling with a transmission peak equal to 1 (unity resonance) and resonant tunneling with a transmission peak less than 1 (below unity resonance) may occur in the unsymmetrical double-barrier structures. Two independent conditions are required for unity-resonant transmission: One is the Phase-Difference Condition for Resonance (PDCR) and the other is the Maximum Condition for the Peak Value (MCPV). The below-unity resonant transmission occurs when only condition PDCR holds. It is believed that the two conditions are useful for calculating values of the transmission coefficient and the resonance energy for the unsymmetrical double-barrier structures. They may be useful for resonant tunneling-device fabrication. Furthermore, wave functions of an electron at resonance level are calculated and the confining phenomenon is confirmed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica solida Sinica 9 (1996), S. 179-183 
    ISSN: 0894-9166
    Keywords: crack growth ; stability ; cusp catastrophe ; J-integral ; three-point bending specimen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper presents an attempt at the application of catastrophe theory to the stability analysis ofJ-controlled crack growth in three-point bending specimens. By introducing the solutions ofJ- integral in the completely yielding state for the ideal plastic material, the critical condition of losing stability for the crack propagation in the specimen is obtained, based on the cusp catastrophe theory. The process of the crack growth from geometrical sense is described.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 65 (1997), S. 484-490 
    ISSN: 1090-6487
    Keywords: 73.40.Gk ; 73.20.Dx ; 72.15.Eb ; 71.20.Be
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new mechanism is proposed for the anomalous tunneling transmittance of a double-barrier quantum-well structure doped with a transition-metal impurity and possessing an intrinsic two-dimensional continuum. The new tunneling channels are due to exponentially-narrow single-particle resonances arising near the edge of a 2D band during tunneling. They are temperature-independent and their contribution to the transmittance can exceed the contribution of the Kondo resonance even at temperatures T〈T K .
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    ISSN: 1090-6487
    Keywords: 73.40.Kp ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Electron transport through an asymmetric heterostructure with a two-step barrier N+GaAs/N−GaAs/Al0.4Ga0.6As/Al0.03Ga0.97As/N−GaAs/N+GaAs was investigated. Features due to resonance tunneling both through a size-quantization level in a triangular quantum well, induced by an external electric field in the region of the bottom step of the barrier (Al0.03Ga0.97As layer), and through virtual levels in two quantum pseudowells of different width are observed in the tunneling current. The virtual levels form above the bottom step or above one of the spacers (N−GaAs layer) as a result of interference of electrons, in the first case on account of reflection from the Al0.4Ga0.6As barrier and a potential jump at the Al0.03Ga0.97As/N−GaAs interface and in the second case — from the Al0.4Ga0.6As barrier and the potential gradient at the N−GaAs/N+GaAs junction, reflection from which is likewise coherent.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 67 (1998), S. 196-202 
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.23.Hk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A model is found whereby the Coulomb interaction during electron transport in quantum wires of finite length with current-lead contacts can be taken into account exactly (within the framework of the bosonization method). It is established that the charge density distribution along a wire in the case of the real Coulomb interaction is strongly different from the Luttinger liquid model, where the interaction is assumed to be short-ranged. The charge density near the contacts is found to be much higher than in the model with a short-range interaction, but away from the contacts the two densities are closer to each other.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    ISSN: 1090-6487
    Keywords: 42.55.Px ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A solution of the nonstationary Schrödinger equation describing the resonance interaction of electrons with a weak rf field is found for asymmetric triple-barrier resonance-tunneling structures with thin, high barriers, and an expression is obtained for the active weak-signal conductivity of such structures. It is found that in a number of cases the probability of quantum resonance transitions from an upper to a lower level can increase sharply when the lower levels are shifted relative to one another.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 68 (1998), S. 915-921 
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.61.−r
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is found that various kinds of shell structure which occur at specific values of the magnetic field lead to the disappearance of the orbital magnetization for particular magic numbers in small quantum dots with electron number A〈30.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    ISSN: 1090-6487
    Keywords: 81.15.Hi ; 73.20.Dx ; 68.65.+g
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The characteristic features of electronic spectra in Ge/Si (100) heterostructures obtained by molecular-beam epitaxy are investigated by capacitance spectroscopy. It is observed that the self-organization of a Ge film into an island film when the effective germanium thickness exceeds six monolayers is accompanied by the appearance of hole bound states, which can be attributed to size quantization and the Coulomb interaction of carriers in the array of Ge quantum dots.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 68 (1998), S. 673-678 
    ISSN: 1090-6487
    Keywords: 74.20.−z ; 73.20.Dx ; 74.25.Ha ; 11.30.Pb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the theory of mesoscopic superconductivity it is necessary to supplement the coordinates x, y, z with some additional physical characteristics (coordinates) of free space. An adequate description of mesoscopic superconductivity is obtained by introducing a nonrelativistic version of Grassmann spinor coordinates, which are studied in supersymmetric field theories and convert ordinary space into superspace. An experimental check of the proposed description of the superconducting and magnetic properties of metallic nanoparticles would provide a direct confirmation of the concept of superspace.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.40.Hm ; 84.37.+q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that capacitance spectroscopy can be used to investigate the spin polarization of two-dimensional electronic systems (2DESs). We employed this method to investigate the spin polarization of 2DESs in a GaAs/AlGaAs heterojunction for filling factors of the magneticquantization levels 0.28〈ν〈0.9. It is proved that in the presence of states of the fractional quantum Hall effect with ν f =1/3 and 2/3 the ground state of a 2DES with ν〉2/3 is incompletely spin-polarized.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 71.35.−y ; 33.15.Pw
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The experimental results of a study of the fine structure of the levels of excitons localized in InAlAs quantum dots in an AlGaAs matrix are reported. Transformations from optical orientation to alignment and from alignment to orientation, which occur due to the exchange splitting of a dipole-active excitonic doublet and are allowed by the low symmetry of a quantum dot, are observed in a longitudinal magnetic field (Faraday geometry). A comparison of theory with experiment for a self-organized ensemble of quantum dots enables a determination of the character of the distribution over the dipole orientations for resonance optical transitions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    ISSN: 1090-6487
    Keywords: 73.20.Mf ; 73.20.Dx ; 78.55.Cr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Photoluminescence spectra of interwell excitons in double GaAs/AlGaAs quantum wells (n-i-n structures) have been investigated (an interwell exciton in these systems is an electron-hole pair spatially separated by a narrow AlAs barrier). Under resonance excitation by circularly polarized light, the luminescence line of interwell excitons exhibits a significant narrowing and a drastic increase in the degree of circular polarization of photoluminescence with increasing exciton concentration. It is found that the radiative recombination rate significantly increases under these conditions. This phenomenon is observed at temperatures lower than the critical point and can be interpreted in terms of the collective behavior of interwell excitons.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 71 (2000), S. 391-394 
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 03.65.−w
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The two-electron dynamics in a symmetric double quantum dot placed in a onstant electric field is considered. It is shown that, despite the Coulomb blockade, interdot electron-density oscillations are possible. In these oscillations, a charge equal to the charge of a single electron is periodically transferred from one quantum dot to the other.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 65 (1997), S. 253-258 
    ISSN: 1090-6487
    Keywords: 71.45.Gm ; 73.20.Dx ; 73.40.Lq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that the phase transition of density-wave origin in homogeneous liquids is preceded by fermion condensation. Thus fermion condensation may be observed in low-density electron liquids, neutron stars, and liquid He3. Three-dimensional (3D) and two-dimensional (2D) liquids are considered.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 68 (1998), S. 669-672 
    ISSN: 1090-6487
    Keywords: 71.35.Ji ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The ground state of a spatially indirect exciton in type-II quantum dots with a short-range potential acquires nonzero angular momentum in the presence of a magnetic field oriented perpendicular to the plane of the system. The critical magnetic field of the transition to a ground state with nonzero angular momentum depends on the radius of the quantum dot. Such a transition can be observed as quenching of luminescence by a magnetic field in quantum dots of the GaSb/GaAs system, for example.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 66 (1997), S. 431-436 
    ISSN: 1090-6487
    Keywords: 72.20.My ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A study is made of the four-terminal Hall junction under the influence of a radiation field. The frequency of the radiation field is tuned to a transition between the energy of a bound state below a conduction subband and the Fermi energy of the incident electrons. Radiation-field-induced resonant dips of the Hall resistance are exhibited at low magnetic fields.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    ISSN: 1090-6487
    Keywords: 85.30.Vw ; 73.20.Dx ; 78.30.Fs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The spontaneous emission of far-infrared radiation (λ≅10–20 μm) from diode structures with vertically coupled InGaAs/AlGaAs quantum dots is observed. This emission is due both to transitions of holes and electrons between size-quantization levels in quantum dots and to transitions from the continuum to a level in a quantum dot. It is observed only when accompanied by lasing at short wavelengths (λ≅0.94 μm) and, like the short-wavelength emission, it exhibits a current threshold. The spontaneous emission of long-wavelength radiation is also observed in InGaAs/GaAs quantum-well laser structures. This radiation is approximately an order of magnitude weaker than that from quantum-dot structures, and it has no current threshold.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 67 (1998), S. 1069-1075 
    ISSN: 1090-6487
    Keywords: 71.10.Hf ; 71.27.+a ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that additional scattering due to tunneling induces a transition of the system from a non-Fermi-liquid into a Fermi-liquid state as the distance between the Fermi level in the walls and the 2D-band edge is varied in a double-barrier quantum well, doped with transition-metal impurities and having an intrinsic two-dimensional continuum.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    ISSN: 1090-6487
    Keywords: 75.60.Nt ; 75.60.Ch ; 75.70.Cn ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that under resonance tunneling conditions the energy structure of electric-field domains in doped superlattices is substantially different from a resonance structure. As the impurity concentration decreases, the domain walls become wider and the current hysteresis becomes narrower (collapses) as a result of the mismatch of the resonance levels in the region of a domain wall. A physical interpretation of the criterion for the existence of electric-field domains is given.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    ISSN: 1090-6487
    Keywords: 73.40.Hm ; 72.15.−v ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effect of the nuclear hyperfine interaction on the dc conductivity of 2D electrons under quantum Hall effect conditions at filling factor ν=1 is observed for the first time. The local hyperfine field enhanced by dynamic nuclear polarization is monitored via the Overhauser shift of the 2D conduction electron spin resonance in AlGaAs/GaAs multiquantum-well samples. The experimentally observed change in the dc conductivity resulting from dynamic nuclear polarization is in agreement with a thermal activation model incorporating the Zeeman energy change due to the hyperfine interaction. The relaxation decay time of the dc conductivity is, within experimental error, the same as the relaxation time of the nuclear spin polarization determined from the Overhauser shift. These findings unequivocally establish the nuclear spin origins of the observed conductivity change.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.20.Hb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A radical change in the ionization energy of the donor impurity Si in a GaAs/AlGaAs double-well heterostructure is observed experimentally when the electronic wave function is relocated in an electric field. The ionization energy of the impurity decreases from 15.5 meV to 0 when the voltage across the structure changes by less than 1 V. The Stark effect would give a change in the ionization energy of not more than 3 meV.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 69 (1999), S. 250-254 
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 61.46.+w
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A study is made of the Förster energy transfer from an excited semiconductor quantum dot to an organic material surrounding the dot. A quantum-mechanical microscopic description of a Wannier-Mott exciton in a quantum dot is employed together with a macroscopic description of the organic medium. The calculations show that for II–VI semiconductors such transfer can occur in a time of the order of tens of picoseconds, which is much shorter than the lifetime of an excitation in a quantum dot in the absence of transfer. Therefore, just as for quantum wells, the energy transfer mechanism considered can be a quite efficient means for pumping organic sources of radiation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 64 (1996), S. 460-466 
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 76.40.+b
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A number of effects associated with the curvature of the surface on which a two-dimensional (2D) electron gas is placed are studied. The most significant effect in an external magnetic field (which for 2D electrons becomes effectively nonuniform) is the lifting of the degeneracy of the Landau levels. The intensity and shape of the cyclotron resonance line (inhomogeneously broadened) for different polarizations and the corrections to the Hall constant are found for the example of a circular cylinder. A picture of the quantization of the conductance that is qualitatively different from the case of a flat strip is obtained for a quasi-one-dimensional quantum wire in the form of a hollow cylinder. It is shown that in contradistinction to the planar case the spectrum of 2D electrons on the curved surface is sensitive to the sign of the spin-orbit coupling constant (for a fixed sign of the curvature). For hetero-junctions, for example, this opens up new possibilities for extracting information about their “hidden parameters.”
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 64 (1996), S. 592-600 
    ISSN: 1090-6487
    Keywords: 72.90.+y ; 73.20.Dx ; 73.40.−c ; 73.90.−f
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Macroscopic charge quantization is analyzed in the case in which thermal activation across trapping barriers dominates over tunneling and the barrier heights are comparable to the charging and thermal energies. Barrier suppression, the image force due to the finite electron charge, and the contribution of unstable charge states are considered. The effects considered may partly account for recent experimental data on high-temperature single-electronics in semiconductor and granulated systems.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    ISSN: 1090-6487
    Keywords: 73.61.Ey ; 73.40.Kp ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The transformation of quantum size levels into virtual levels upon a change in the electric field in an AlAs/GaAs superlattice located in the i region of a p-i-n structure is studied experimentally and theoretically. It is shown that an interfacial state at the boundary between the superlattice and the p-GaAs contact layer results in a resonant increase in the probability of photoelectron tunneling from the contact into the superlattice via Wannier-Stark levels.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 70 (1999), S. 390-395 
    ISSN: 1090-6487
    Keywords: 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that when a strong ac electric field acts on an electron in a double quantum well, the dipole moment is an almost periodic function of the dc voltage applied to the structure. An antipolarization effect — the structure is polarized in a direction opposite to the external field — appears during one half of the period.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 70 (1999), S. 410-414 
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 71.10.Ca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Landau quantization for the electron gas on the surface of a sphere is considered. It is shown that in the regime of strong fields the lowest energy states are those with magnetic quantum numbers m of order of Φ /Φ0, the number of magnetic flux quanta piercing the sphere. For an electron gas of low density (semiconducting situation) it leads to the formation of an electronic stripe on the equator of the sphere in high fields.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    ISSN: 1090-6487
    Keywords: 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract When a voltage is applied to double quantum wells based on AlGaAs/GaAs heterostructures with contact regions (n-i-n structures), a two-dimensional (2D) electron gas appears in one of the quantum wells. Under illumination which generates electron-hole pairs, the photoexcited holes become localized in a neighboring quantum well and recombine radiatively with the 2D electrons (tunneling recombination through the barrier). The appearance, ground-state energy, and density of the degenerate 2D electron gas are determined from the structure of the Landau levels in the luminescence and luminescence excitation spectra as well as from the oscillations of the radiative recombination intensity in a magnetic field with detection directly at the Fermi level. The electron density is regulated by the voltage between the contact regions and increases with the slope of the bands. For a fixed slope of the bands the 2D-electron density has an upper limit determined by the resonance tunneling of electrons into a neighboring quantum well and subsequent direct recombination with photoexcited holes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 65 (1997), S. 909-914 
    ISSN: 1090-6487
    Keywords: 78.20.Bh ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The optical orientation of electron spins in heavily doped semiconductor structures with a valence band that is split as a result of size quantization or uniaxial deformation is investigated theoretically. It is shown that lowering the Fermi level by doping and by lowering the temperature should lead to sharp changes in the photon-energy-dependence of the average spin of the excited electrons in structures excited by circularly polarized light. This effect is due to an interchange of the dominant contribution of transitions from a light-hole subband and transitions from the heavy-hole subband in absorption.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 65 (1997), S. 215-216 
    ISSN: 1090-6487
    Keywords: 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Quantum dots based on materials with long-lived terahertz vibrations are studied. It is shown that squeezed states of such vibrations can result in microwave-frequency modulation of the optical radiation absorbed at electronic transitions in quantum dots.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    ISSN: 1090-6487
    Keywords: 73.61.Ey ; 73.20.Dx ; 07.79.Fc ; 61.16.Ch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study InP quantum dots which are prepared by strain induced self-assembly on GaAs substrates with a GaInP buffer layer using a near field scanning optical microscope operating at near liquid He bath temperatures in the collection mode. Single quantum dots are identified spatially and spectrally due to their photoluminescence spectrum. Series of luminescence lines due to single dots of different sizes are discussed in terms of dot height and width fluctuations.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 71.35.Cc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Screening of excitonic states by a system of 2D electrons (or holes) in GaAs/AlGaAs single quantum wells is studied. With increasing concentration of 2D charge carriers, a threshold-type disappearance of excitonic states is observed in both luminescence and reflectance spectra. The higher the quality of the 2D system, the lower the corresponding threshold concentration. In the best systems, the collapse of excitonic states occurs at unexpectedly low electron densities n e =5×109 cm−2, which correspond to the mean dimensionless distance between the particles r s =8. This value far exceeds the threshold values observed for 3D systems (r s ≈2), as well as the values obtained for quantum wells in previous studies. The problem of measuring the concentration of low-density 2D charge carriers in photoexcitation conditions is solved by applying the method of optical detection of the dimensional magnetoplasma resonance. This method provides reliable measurements of the density of a 2D system to the values about 109 cm−2.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 66 (1997), S. 298-303 
    ISSN: 1090-6487
    Keywords: 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The possibility of performing single-electron computing without dissipation in an array of tunnel-coupled quantum dots is studied theoretically, taking the spin gate NOT (inverter) as an example. It is shown that the logical operation can be implemented at the stage of unitary evolution of the electron subsystem, although complete switching of the inverter cannot be achieved in a reasonable time at realistic values of model parameters. The optimal input magnetic field is found as a function of the interdot tunneling energy and intradot Coulomb repulsion energy.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.20.Mf ; 78.60.−b ; 78.55.Cr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The radiative recombination spectra of two-dimensional electrons with free photoexcited holes are investigated for a wide variety of GaAs/ AlGaAs quantum wells, with different thicknesses and electron densities. It is found that for certain, close to integral, filling factors an intense line corresponding to an Auger process — radiative recombination with the emission of an additional magnetoplasmon — appears in the luminescence spectrum. The new line is shifted to lower energies with respect to the zero Landau level, and the magnetic field dependence of the energy splitting between these lines agrees with the theoretical concepts of the dispersion of magnetoplasmon excitations. This makes it possible to estimate the magnetoplasmon energy at the roton minimum.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    ISSN: 1090-6487
    Keywords: 78.66.Fd ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Terahertz emission accompanying heating of two-dimensional electrons by a strong electric field applied along size-quantized GaAs/AlGaAs layers is observed and investigated. The emission is due to indirect optical transitions of hot electrons in the bottom size-quantization band. The experimentally obtained emission spectra are compared with the spectra calculated taking into account scattering of electrons by optical phonons, impurities, and interfacial roughness and electron-electron scattering. Satisfactory agreement is obtained. The temperature of the hot electrons is determined from a comparison of the spectra.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 42.50.Gy ; 33.80.Be
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A mechanism is proposed for obtaining intraband population inversion of electrons in size-quantization levels through the injection of electron-hole pairs into the i region of a heterostructure with quantum wells or quantum dots. Key elements of the mechanism are the simultaneous generation of interband (hv≈E g ) near-IR radiation and the presence of a “metastable” level. In quantum wells such a level can be produced by making use of the weak overlap of the wave functions of electrons in the levels of a quantum well of complicated configuration and exploiting the characteristic features of the interaction of electrons with optical phonons in polar semiconductors. In quantum dots such a level forms as a result of the phonon bottleneck effect. Estimates are made of the gain for mid-IR radiation in intraband optical transitions of electrons.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    ISSN: 1090-6487
    Keywords: 73.61.Ph ; 73.50.−h ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Light-induced conformational transformations of the naphthacenequinone (NQ) molecules are observed by scanning tunneling microscopy (STM). NQ molecules packed in a Langmuir-Blodgett (LB) film are shown to form stable ordered structures on a surface of highly oriented pyrolytic graphite (HOPG). The local density of electronic states is found to exhibit the distinct peak which is characteristic of two-dimensional conductivity. An additional subband of empty electronic states is found for NQ molecules in form A but not in form B. The constant-height STM images of individual molecules in form A demonstrate an additional structure that is indicative of a conformational transition of the NQ molecules. This transition involves the transfer of the phenoxy group from one oxygen to another.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 64 (1996), S. 231-236 
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 84.30.Bv ; 85.30.Vw
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new approach to the implementation of certain logical functions in quantum-dot gates for single-electron computing is proposed. It is shown that placing a gate in a uniform external magnetic field allows one to construct gates with 1) symmetric physical truth tables and 2) large (in some cases close to saturated) absolute magnitude of the average spin at the output dots. Thus two serious obstacles are removed which otherwise could present a problem in the fabrication of a set of coupled quantum-dot gates.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 68 (1998), S. 732-737 
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.40.Hm ; 75.70.Cn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Self-induced filamentation of the current near the edges of a sample in the Hall geometry has been observed in the quantum-Hall-effect regime in a two-dimensional electronic system arising near a GaAs/AlGaAs heterojunction. If in the case of integer values of the filling factor ν averaged over the sample the currents flowing along opposite edges are approximately the same, then away from such a value within the quantum plateau the current is increasingly concentrated near that edge of the sample where the local value of ν is closer to being an integer. When the direction of the magnetic field or of the current changes, the filament switches to the opposite edge of the sample.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    ISSN: 1090-6487
    Keywords: 73.20.Mf ; 73.20.Dx ; 85.30.Mn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effect of absorption of nonequilibrium acoustical phonons on the intensity of recombination of a two-dimensional electron gas in a magnetic field is investigated. The nonequilibrium acoustical phonons are emitted in the relaxation of electrons in a tunnel junction deposited on the back side of a sample with a two-dimensional electronic channel. It is demonstrated that the optical signal showing the intensity of the recombination of nonequilibrium electrons from a photoexcited size-quantization subband can serve as a sensitive detector of acoustical phonons. Because the general heating of two-dimensional carriers and the intersubband transitions stimulated by the absorption of nonequilibrium acoustical phonons lead to effects of different sign, the useful signal can be discriminated unambiguously.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 68.65.+g ; 71.35.−y
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The change in the properties of excitonic states near anticrossing is investigated experimentally. It is shown that the phase relaxation time of light excitons in a GaAs/AlGaAs symmetric double quantum well increases by a factor of five as a result of mixing of the energy states of light and heavy excitons.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 71.20.Gj ; 61.44.Br
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The nature of two-dimensional incommensurate superlattices Ll2 (MM) obtained in the precious-metals alloys Au3 Cu and Cu3 Pd is investigated on the basis of first-principles calculations of the electronic structure. It is shown that their stability can be explained by the opening of energy gaps on coinciding sections of the Fermi surface in two mutually perpendicular directions. It is important that this explanation holds only if the superlattice is treated as a superstructure with respect to ordinary superstructures (Ll2): the electronic spectrum of the superstructure and not the disordered alloy (as in the existing electronic theory of one-dimensional long-period structures) should serve as the starting spectrum. Arguments supporting the fact that in a number of quasicrystal-line substances the Ll2 (MM) phases fall between incommensurate systems and quasicrystals are presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 71 (2000), S. 422-425 
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.40.Hm ; 71.45.Lr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new class of collective states, which are assumed to be due to the spontaneous formation of a charge density wave (“striped” phase) upon filling high Landau levels, was recently observed in a 2D electron system based on GaAs/AlGaAs(001). The following unsolved problem is considered in the work: what is the reason for stripe pinning along the crystallographic direction [110]? It is shown that the effective mass of 2D electrons is anisotropic for a single heterojunction (001) A 3 B 5. This natural anisotropy is due to the C 2v symmetry of the heterointerface and, even being weak (0.1%), can govern the stripe direction. A magnetic field parallel to the interface induces “magnetic” anisotropy of effective mass. The competition of these two types of anisotropy (natural and magnetic) provides a quantitative description of the experiment.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 71 (2000), S. 191-194 
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.50.−h; 73.61.−r
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We studied a biased superlattice and revealed a considerable current response to irradiation by non-equilibrium acoustic phonons with an effective temperature on the order of a few Kelvins. We discuss two phonon source-superlattice configurations, for which the current response is caused by either interwell or intrawell electron transitions. We have shown that the response is sensitive to both direction and spectral distribution of phonons. The results explain recent experiments on the phonon-induced current response and prove that the superlattices can be used for the characterization of a high-frequency phonon flux.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 33.50.Dq ; 78.66.−w
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The luminescence spectra of GaAs/AlGaAs quantum wells (QWs) with low-density quasi-two-dimensional electron and hole channels were studied. It was demonstrated that, at temperatures below some critical value (T c ∼30 K) and for an excitation power lying in a certain temperature-dependent range, two metastable charge states with two-dimensional charge densities differing in both magnitude and sign can occur in the system under the same conditions. The obtained experimental data agree well with the mathematical model allowing for the transfer of photoexcited carriers to the barrier followed by their tunneling into QW.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    ISSN: 1090-6487
    Keywords: 71.55.Jv ; 73.20.Dx ; 78.66.−w
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Absorption and luminescence of the quantum wells formed by the (Zn-Cd)Se and (Ga-In)As solid solutions are studied in the range of exciton size-quantization ground state. The spectra observed are described by a model assuming the two-dimensional character of fluctuation states in quantum wells and the presence of a percolation threshold within the absorption contour.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.40.Hm ; 78.66.−w ; 05.40.−a
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Anomalous intensity fluctuations are observed in the spectrum of radiative ecombination of quasi-two-dimensional (2D) electrons with photoexcited holes in a single quantum well. The fluctuations are observed exclusively under the conditions of the quantum Hall effect (QHE). It is shown that, if the QHE conditions are not fulfilled, the radiation intensity fluctuates strictly following the Poisson distribution 〈δN 2〉/〈N〉= 1), whereas in the QHE regime the fluctuation amplitude increases by several orders of magnitude (〈δ N 2〉/〈N〉∼102). It is demonstrated that the maxima of the emission noise amplitude coincide with the maxima of inverse magnetoresistance of 2D electrons in the QHE regime and correspond to establishing an anomalously high uniformity of the system.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 66 (1997), S. 588-593 
    ISSN: 1090-6487
    Keywords: 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In low-dimensional systems with an asymmetric quantizing potential, an asymmetric electron energy spectrum ε(p)≠ε(−p), where p is the electron momentum, arises in the presence of a magnetic field. A consequence of such an energy spectrum is that momentum transfer to the electron system in mutually opposite directions in the presence of an external perturbation is different. Therefore, in the presence of a standing electromagnetic wave momentum is transferred from the wave to the electrons, which gives rise to a new type of electromotive force.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.50.Mx ; 76.70.Hb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Dimensional magnetoplasma resonance is observed and studied in a spatially confined, two-dimensional hole system in (001) GaAs/AlGaAs single quantum wells. From the analysis of the field dependence of the magnetoplasma resonance on the diameter of the 2D system, the semiclassical cyclotron hole mass is determined. Its value is found to be equal to 0.26m 0 (m 0 is the free electron mass), which considerably exceeds the theoretically predicted value. A method is proposed for a direct determination of the concentration and mobility of 2D holes from the analysis of the magnetoplasma resonance.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    ISSN: 1090-6487
    Keywords: 72.15.Gd ; 72.20.My ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new phenomenon is observed experimentally in a heavily doped asymmetric quantum-size structure in a magnetic field parallel to the quantum-well layers — a transverse magnetoresistance which is asymmetric in the field (there can even be a channge in sign) and is observed in the case that the structure has a built-in lateral electric field. A model of the effect is proposed. The observed asymmetry of the magnetoresistance is attributed to an additional current contribution that arises under nonequilibrium conditions and that is linear in the gradient of the electrochemical potential and proportional to the parameter characterizing the asymmetry of the spectrum with respect to the quasimomentum.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    ISSN: 1090-6487
    Keywords: 73.61.Ey ; 73.20.Dx ; 63.22.+m
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The energy splitting of fundamental localized transverse optical (TO1) phonon modes in GaAs/AlAs superlattices and quantum wires grown by molecular-beam epitaxy on a faceted (311)A GaAs surface is observed by Raman spectroscopy. The form of the Raman scattering tensor makes it possible to observe the TOx and TOy modes separately, using different scattering geometries the y and x axes are the directions of displacement of the atoms and are directed parallel and transverse to the facets on the (311)A surface). Enhancement of the splitting of the TO1x and TO1y modes is observed as the average thickness of the GaAs layers is decreased from 21 to 8.5 Å. The splitting is probably due to the effect of the corrugation of the GaAs/AlAs (311)A hetero-interface on the properties of localized phonon modes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.40.Hm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that the characteristic features of the chemical potential for 2D electrons in a magnetic field, which lead to sharp dips in the magnetic field dependence of the capacitance of a 2D system, also affect the electrostatic potential distribution in the direction of the transport current flowing through a 2D Corbino disk under conditions of integral magnetic filling factor. The associated details of the temperature dependence of the electrostatic potential distribution, the distances to the screening electron, and the transport potential difference at the Corbino edges are investigated. The possibilities of experimentally observing these features of the electrostatic potential distribution along a Corbino disk with a transport current under conditions of the quantum Hall effect are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.40.Hm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We employ a magnetocapacitance technique to study the spectrum of the soft two-subband (or double-layer) electron system in a parabolic quantum well with a narrow tunnel barrier at the center. In this system, when unbalanced by gate depletion, two sets of quantum oscillations are observed at temperatures T≳30 mK: one originates from the upper electron subband in the closer-to-the-gate part of the well, and the other indicates the existence of common gaps in the spectrum at integer fillings. For the lowest filling factors υ=1 and υ=2, both the presence of a common gap down to the point of the one-to two-subband transition and their nontrivial magnetic field dependences point to magnetic-field-induced hybridization of electron subbands.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    ISSN: 1090-6487
    Keywords: 78.66.Fd ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The interwell radiative recombination from biased double quantum wells (DQW) in pin GaAs/AlGaAs heterostructures is investigated at different temperatures and external electrical fields. The luminescence line of interwell recombination of spatially separated electron-hole pairs exhibits systematic narrowing with temperature increase from 4.5 to 30 K. A theoretical model is presented which explains the observed narrowing in terms of lateral thermally activated tunneling of spatially separated e-h pairs localized by random potential fluctuations in the quantum wells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 71.35.Cc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The recombination spectra of excitons and excitonic complexes in un-doped GaAs/AlGaAs single quantum wells are investigated. It is shown on the basis of a study of the magnetic-field dependence of the emission spectra and the degree of optical orientation in zero magnetic field and on the basis of electrooptic measurements that not only the density but also the sign of the charge carriers in a well depend strongly on the photoexcitation energy. It is shown on the basis of a comparative analysis of the spin splitting of the recombination lines of free and bound excitons that the recombination line which was attributed earlier to a positively charged exciton corresponds to the recombination of an exciton bound on a neutral acceptor.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 68 (1998), S. 662-668 
    ISSN: 1090-6487
    Keywords: 85.30.Mn ; 73.20.Dx ; 73.20.Mf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Resonant tunneling is accompanied by the accumulation of 2D electrons in the quantum well between the barriers of resonant tunneling diodes. In high-quality structures this gives a Z-shaped current-voltage characteristic, and it is shown that self-excitation of 2D plasmons occurs in this quantum well for any external circuit at completely realistic parameters of the structures.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 69 (1999), S. 616-622 
    ISSN: 1090-6487
    Keywords: 71.35.Lk ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effect of a random field due to impurities, boundary irregularities, and so on, on the superfluidity of a three-dimensional system of excitons and a quasi-two-dimensional system of direct or spatially indirect excitons is studied. The influence of a random field on the density of the superfluid component in the indicated excitonic systems at low temperatures T is investigated. The interaction between excitons is taken into account in the ladder approximation. For quasi-two-dimensional excitonic systems in a random field the Kosterlitz-Thouless temperature in the superfluid state is calculated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 70 (1999), S. 488-490 
    ISSN: 1090-6487
    Keywords: 73.40.Kp ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nonlinear waves in a two-dimensional electronic plasma with metal screening gates are investigated. It is shown that solitons described by the KdV equation exist in such a system.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 71 (2000), S. 111-113 
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.61.−r
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We developed the theory of Coulomb drag current induced in a one-dimensional nanowire by the ballistic nonohmic current in a nearby parallel nanowire under the ballistic transport regime. As in the ohmic case, we predict sharp oscillations of the drag current as a function of gate voltage or chemical potential of electrons. We also study the dependence of drag current on the voltage V across the driving wire. For relatively large values of V, the drag current is proportional to V 2.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    ISSN: 1090-6487
    Keywords: 07.60.Ly ; 73.23.Ad ; 73.20.Dx ; 73.50.−h
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract For a ballistic ring interferometer based on high-mobility two-dimensional electron gas in an AlGaAs/GaAs heterojunction, the electrostatic potential and the energy spectrum are determined. It is shown that the splitting points in such an interferometer have the form of triangular potential wells. Calculation is performed for the two-dimensional electron transmission through the ring, and the Fano resonances caused by the coupling of the transmitted waves with the levels of higher transverse modes in triangular wells are predicted. These resonances are observed in the experiment.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    ISSN: 1090-6487
    Keywords: 71.55.Eq ; 61.16.Ch ; 68.65.+g ; 68.35.Bs ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Interaction of two localized impurity states of Si atoms at a GaAs surface was studied by scanning tunneling microscopy and spectroscopy. The effects of a twofold “switching” on and off of the states of each of the interacting atoms, the tunneling-interaction-induced mutual level pulling of these states, and the level stabilization near E F were observed. These effects are explained in terms of the extended Anderson model.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    Springer
    JETP letters 72 (2000), S. 312-315 
    ISSN: 1090-6487
    Keywords: 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The strains in rolled InAs/GaAs heterostructures of nanometer sizes are calculated. It is shown that the strain distributions in nanotubes (structures with coherently bounded rolls) and nanoscrolls are essentially different, resulting in different energy spectra of the charge carriers. Photogenerated electrons and holes in nanotubes can be spatially separated across the wall width.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    ISSN: 1090-6487
    Keywords: 73.20.Dx ; 73.50.Rb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nonlinear interaction of an intense surface acoustic wave (SAW) with a 2D electron-hole plasma generated by light in a semiconductor quantum well near a piezoelectric crystal is investigated. It is shown that, in a strongly nonlinear regime, the acoustoelectric interaction is enhanced because of the accumulation of carriers in the field of an intense SAW. In addition, in a strongly nonlinear regime, the dissipation of the acoustic wave energy increases and the sound velocity decreases. These dependences fundamentally differ from those observed in a unipolar plasma. For high sound intensities, analytical results are obtained.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    ISSN: 1432-0770
    Keywords: Key words: Hebbian learning rule ; attractor dynamics ; symmetric connections ; multiplicative normalization ; self-organization ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract. While learning and development are well characterized in feedforward networks, these features are more difficult to analyze in recurrent networks due to the increased complexity of dual dynamics – the rapid dynamics arising from activation states and the slow dynamics arising from learning or developmental plasticity. We present analytical and numerical results that consider dual dynamics in a recurrent network undergoing Hebbian learning with either constant weight decay or weight normalization. Starting from initially random connections, the recurrent network develops symmetric or near-symmetric connections through Hebbian learning. Reciprocity and modularity arise naturally through correlations in the activation states. Additionally, weight normalization may be better than constant weight decay for the development of multiple attractor states that allow a diverse representation of the inputs. These results suggest a natural mechanism by which synaptic plasticity in recurrent networks such as cortical and brainstem premotor circuits could enhance neural computation and the generation of motor programs.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Springer
    Journal of nonlinear science 5 (1995), S. 373-418 
    ISSN: 1432-1467
    Keywords: Hamiltonian system with symmetry ; relative equilibria ; perturbation ; linearization ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Summary A relative equilibrium of a Hamiltonian system with symmetry is a point of phase space giving an evolution which is a one-parameter orbit of the action of the symmetry group of the system. The evolutions of sufficiently small perturbations of a formally stable relative equilibrium are arbitrarily confined to that relative equilibrium's orbit under the isotropy subgroup of its momentum. However, interesting evolution along that orbit, here called drift, does occur. In this article, linearizations of relative equilibria are used to construct a first order perturbation theory explaining drift, and also to determine when the set of relative equilibria near a given relative equilibrium is a smooth symplectic submanifold of phase space.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Springer
    Interface science 3 (1996), S. 303-316 
    ISSN: 1573-2746
    Keywords: epitaxy ; Krudjumov-Sachs ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In this paper we address the problems related to critical misfit and thickness in epilayer-substrate combinations of comparable bond strengths; specifically the case in which a pseudomorphic monolayer (ML) is stable and the critical thickness is about three MLs or less. Of particular interest are the average energies related to misfit strain f KS and misfit dislocations (MDs)—in the latter case the individual contributions of the oscillatory strains 〈V〉 and the epilayer-substrate disregistry 〈V〉MD. The individual energies are of interest because they may play different roles in the realization of specific growth modes. The analytical approach involves the following assumptions: (a) a rigid substrate as source of a periodic epilayer atom-substrate interaction potential which we model in terms of a low order truncated Fourier series; and (b) an epilayer which (i) deforms harmonically with zero strain gradient normal to the film plane, (ii) grows in Kurdjumov-Sachs (KS) orientation due to small misfit. f KS and in the layer-by-layer growth mode. Arguments are presented claiming that this interfacial situation may be approximated by a one-dimensional problem in which epilayer stiffness constants and equilibrium structure, as well as epilayer-substrate interaction depend on epilayer thickness; which poses a complex problem. An approximate solution could be obtained by assuming these quantities to be independent of thickness and proximities of the vacuum and the substrate. The most prominent conclusions are that the equilibrium density of MDs and hence the transition from misfit accommodation by MS to one containing MDs is a catastrophic process and that sustained minimum energy may require the overcoming of an energy barrier. While elementary implementation of the results to equilibrium growth mode theory suggests—independently of the catastrophic nature—that energetically favored misfit strain relief by misfit dislocations may, or may not, effect a transition to Stranski-Krastanov growth, a crude numerical calculation favors the transition. A proper implementation of the results require extensive numerical calculations and is planned for the near future.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica Sinica 12 (1996), S. 124-134 
    ISSN: 1614-3116
    Keywords: jet ; stability ; breakup ; atomization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Based on the linear analysis of stability, a dispersion equation is deduced which delineates the evolution of a general 3-dimensional disturbance on the free surface of an incompressible viscous liquid jet. With respect to the spatial growing disturbance mode, the numerical results obtained from the solution of the dispersion equation reveal that a dimensionless parameterJ e exists. AsJ e〉1, the axisymmetric disturbance mode is most unstable; and whenJ e〈1, the asymmetric disturbances come into being, their growth rate increases with the decrease, ofJ e, till one of them becomes the most unstable disturbance. The breakup of a low-speed liquid jet results from the developing of axisymmetric disturbances, whose instability is produced by the surface tension; while the atomization of a high-speed liquid jet is brought about by the evolution of nonaxisymmetric disturbance, whose instability is caused by the aerodynamic force on the interface between the jet and the ambient gas.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica Sinica 14 (1998), S. 274-282 
    ISSN: 1614-3116
    Keywords: time delay ; stability ; frozen time approach ; retarded dynamic systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract By means of the frozen time approach and the Kronecker product, two criteria of asymptotic stability are derived for the linear, time variant dynamic systems with either short time delays or with weak feedback involving arbitrary time delays, respectively. It is found that the asymptotic stability of these retarded dynamic systems is governed by the maximal and minimal singular values of the coefficient matrices and their time derivatives.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica Sinica 16 (2000), S. 264-272 
    ISSN: 1614-3116
    Keywords: nonlinear dynamics ; bifurcation ; stability ; fluid-solid interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper studies interactions of pipe and fluid and deals with bifurcations of a cantilevered pipe conveying a steady fluid, clamped at one end and having a nozzle subjected to nonlinear constraints at the free end. Either the nozzle parameter or the flow velocity is taken as a variable parameter. The discrete equations of the system are obtained by the Ritz-Galerkin method. The static stability is studied by the Routh criteria. The method of averaging is employed to examine the analytical results and the chaotic motions. Three critical values are given. The first one makes the system lose the static stability by pitchfork bifurcation. The second one makes the system lose the dynamical stability by Hopf bifurcation. The third one makes the periodic motions of the system lose the stability by doubling-period bifurcation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica Sinica 13 (1997), S. 366-376 
    ISSN: 1614-3116
    Keywords: vibro-impact ; stability ; multiplicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The coexisting periodic impacting motions and their multiplicity of a kind of dual component systems under harmonic excitation are analytically derived. The stability condition of a periodic impacting motion is given by analyzing the propagation of small, arbitrary perturbation from that motion. In numerical simulations, the periodic impacting motions are classified according to the system states before and after an impact. The numerical results show that there exist many types of vibro-impacts and the bifurcation of periodic vibro-impacts is not smooth.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica Sinica 14 (1998), S. 226-233 
    ISSN: 1614-3116
    Keywords: jet ; stability ; dispersion equation ; swirling gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Based on the linear analysis of stability, a dispersion equation is deduced which delineates the evolution of a general 3-dimensional disturbance on the free surface of an incompressible viscous liquid jet injected into a gas with swirl. Here, the dimensionless parameterJ e is again introduced, in the meantime, another dimensionless parameterE called as circulation is also introduced to represent the relative swirling intensity. With respect to the spatial growing disturbance mode, the numerical results obtained from solving the dispersion equation reveal the following facts. First, at the same value ofE, in pace with the changing ofJ e , the variation of disturbance and the critical disturbance mode still keep the same characters. Second, the present results are the same as that of S.P. Lin whenJ e 〉1; but in the range ofJ e 〈1, it's no more the case, the swirl decreases the axisymmetric disturbance, yet increases the asymmetric disturbance, furthermore the swirl may make the character of the most unstable disturbance mode changed (axisymmetric or asymmetric); the above action of the swirl becomes much stronger whenJ e ≪1.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    Springer
    Applied mathematics and mechanics 16 (1995), S. 195-202 
    ISSN: 1573-2754
    Keywords: nonlinear ; stability ; Lyapunov function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract In the paper Lyapumov function for a fourth order linear system is given and stability of the trivial solutions to a class of fourth order nonlinear systems is studied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    Springer
    Applied mathematics and mechanics 16 (1995), S. 635-642 
    ISSN: 1573-2754
    Keywords: analytic mechanics ; nonholonomic system ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract The stability for the equilibrium states of Chaplygin's systems is considered. The equations of motion of Chaplygin's systems and the existence conditions of their equilibrium states are given. Some criteria of stability for the equilibrium. states of Chaplygin's systems are obtained. Two examples are finally given.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Springer
    Applied mathematics and mechanics 17 (1996), S. 869-877 
    ISSN: 1573-2754
    Keywords: thermohaline double-diffusive system ; periodic solution ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract A shortout analytic method of stability in strong nonlinear autonomous system is introduced into stability analysis of the thermohaline double-diffusive system. Using perturbation technique obtains conditions of existence and stability for linear and nonlinear periodic solutions. For linear periodic solution in infinitesimal motion, the existence range of monotomic branch and oscillatory branch are outilined. The oscillatory branch of nonlinear periodic solution in finite-amplitude motion has unstable periodic solution when μ is smaller than critical value µ c in this case of 0〈rs-rsc≪1. The stability conclusions under different direction of vortex are drawn out.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    Springer
    Applied mathematics and mechanics 19 (1998), S. 163-168 
    ISSN: 1573-2754
    Keywords: nonlinear equation ; stability ; Newton's method ; auto-adjustable damping method ; the vector of damping factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract The general approach for solving the nonlinear equations is linearizing the equations and forming various iterative procedures, then executing the numerical simulation. For the strongly nonlinear problems, the solution obtained in the iterative process is always difficult, even divergent due to the numerical instability. It can not fulfill the engineering requirements. Newton's method and its variants can not settle this problem. As a result, the application of numerical simulation for the strongly nonlinear problems is limited. An auto-adjustable damping method has been presented in this paper. This is a further improvement of Newton's method with damping factor. A set of vector of damping factor is introduced. This set of vector can be adjusted continuously during the iterative process in accordance with the judgement and adjustment. An effective convergence coefficient and quichening coefficient are employed to relax the restricted requirements for the initial values and to shorten the iterative process. Then, the numerical stability will be ensured for the solution of complicated strongly nonlinear equations. Using this method, some complicated strongly nonlinear heat transfer problems in airplanes and aeroengines have been numerically simulated successfully. It can be used for the numerical simulation of strongly nonlinear problems in engineering such as nonlinear hydrodynamics and aerodynamics, heat transfer and structural dynamic response etc.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    Springer
    Applied mathematics and mechanics 19 (1998), S. 861-867 
    ISSN: 1573-2754
    Keywords: rotating fluids ; motion of body ; small disturbances ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract In this paper, the disturbances to a uniformly rotating ideal fluid with a sphere moving steadily along the axis of rotation are analysed by using linearization theory, the equations of disturbance, pressure and disturbance stream function governing the stability of motion are derived based on the assumption that the flow is rotational symmetric. The equation of disturbance stream function is analysed with the method of normal modes, and the constraints on wave number and wave velocity of the nontrivial neutral disturbances are established and the exact expression of the neutral disturbances are obtained. The conclusion is drawn that three are three kinds of possible forms of neutral disturbances.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    Springer
    Applied mathematics and mechanics 20 (1999), S. 912-916 
    ISSN: 1573-2754
    Keywords: delay ; neural network ; stability ; TN911.23 ; O332
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract In this paper, by using Liapunov functional, some sufficient conditions are obtained for the stability of the equilibrium of a neural network model with delay of the type $$u'_i \left( t \right) = - b_i u_i \left( t \right) + \sum\limits_{j = 1}^n {T_{ij} f_j } \left( {\mu _j u_j \left( {t - \tau _j } \right)} \right) + c_i ,\tau _j \geqslant 0,i = 1,2 \cdots ,n.$$
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    Springer
    Studia geophysica et geodaetica 42 (1998), S. 320-327 
    ISSN: 1573-1626
    Keywords: MHD ; stability ; bifurcations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract A series of numerical studies on the behaviour of magnetic fields and motions in a spherical body of an electrically conducting incompressible fluid have been carried out. The magnetic field was assumed to be maintained by a given electromotive force inside the body and to continue as a potential field in outer space. In view of the motion an external forcing was taken into account, and boundary conditions were considered which correspond to a stress-free surface. The stability of several steady states has been studied as well as the evolutions starting from unstable states. In this paper a configuration with a poloidal magnetic field and a differential rotation, both symmetric about the same axis, is considered. This configuration is stable only for sufficiently small Hartmann numbers but evolves, if disturbed, in the case of larger Hartmann numbers toward a non-axisymmetric state. In this case the well-known symmetrization effect of differential rotation in magnetic fields is destroyed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...