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  • 1
    Electronic Resource
    Electronic Resource
    Tunneling time of spin-polarized electrons in ferromagnet/insulator (semiconductor) double junctions under an applied electric field (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 1318-1323 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Based on the group velocity concept and the two-band model, we investigated tunneling properties of spin-polarized electrons traversing ferromagnetic/insulator (semiconductor) double junctions under the influence of an external electric field. The tunneling time and the transmission coefficient, as well as the spin polarization, were calculated and examined. Effects of the electric field and quantum size are also considered. The results indicate that the tunneling time strongly depends on the spin orientation of tunneling electrons. In a wide range of incident energy, spin-down electrons spend a longer time tunneling through the structure than spin-up ones, and the difference of the tunneling time Δτ between electrons with opposite spin orientation is very sensitive to the incident energy in the lower energy region. Moreover, the variation of Δτ with the increasing of the incident energy shows pronounced oscillations for certain applied bias and structural size. The results also indicate that spin polarization shows frequent wide-range oscillations and its magnitude decays slowly with the increasing of the incident energy, which reveal that the spin polarization in ferromagnetic/insulator (semiconductor) junctions possesses quite different properties from those exhibited in semiconductor electric-barrier or magnetic-barrier structures as well as semiconductor/semimagnetic semiconductor hybrid heterostructures. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1427140
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  • 2
    Electronic Resource
    Electronic Resource
    Finite size effects in carbon nanotubes (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2554-2556 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The low-energy theory for finite long carbon nanotube is derived and numerically examined. It shows that the electronic structure is dominated by the quantum confining, which determines the profile of wave functions as well as the eigen energies; while the details of the wave functions are resolved by the structure of the nanotubes. This behavior is attributed to the peculiar electronic structure of the nanotubes. Because of the slow variation of the profile of electron wave functions, the measured conductance is NOT independent of the position to measure it, which is evident in the multiprobe experiment. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1318241
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  • 3
    Electronic Resource
    Electronic Resource
    Eight-potential-well order-disorder ferroelectric model and effects of random fields (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 3447-3449 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An eight-potential-well order-disorder ferroelectric model was presented and the phase transition was studied under the mean-field approximation. It was shown that the two-body interactions are able to account for the first-order and the second-order phase transitions. With increasing the random fields in the system, a first-order phase transition is transformed into a second-order phase transition, and furthermore, a second-order phase transition is inhibited. However, proper random fields can promote the spontaneous appearance of a first-order phase transition by increasing the overcooled temperature. The connections of the model with relaxors were discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1327612
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  • 4
    Electronic Resource
    Electronic Resource
    Possible order–disorder phase diagrams in (Ax′A1−x″)BO3 and A(Bx′B1−x″)O3 complex perovskites (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 2408-2413 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structural phase diagrams of complex perovskites have been studied within the mean-field approximation. Various phase diagrams with possible topological structures of the 1/2{111}-, 1/2{110}-, and 1/2{100}-type ordered structures are obtained. The 1/2{111}- and 1/2{100}-type ordered structures have similar phase diagrams and their ordering transitions are both of the second kind, while the 1/2{110}-type ordered structure has a more complex phase diagram and its ordering transition is of the first kind. In the two-phase region of the phase diagram, the ordered phase's composition deviates from that of the chemical formula towards the completely ordering composition which is 0.5 for the 1/2{111}-, 1/2{100}-type ordered structures and 0.25, 0.50, 0.75 for the 1/2{110}-type ordered structures. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369558
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  • 5
    Electronic Resource
    Electronic Resource
    Unified model for ordering and staging of intercalated M ions in MxTiS2 (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 819-824 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this article we propose a unified model for ordering and staging of intercalated M ions in the 1T-type intercalation compounds MxTiS2. The ordered structures and the stage structures of M ions occupying octahedrally coordinated interstitial sites are studied using the concentration-wave theory. Ten three-dimensional completely ordered structures have been derived by minimizing the eigenvalue of ionic interaction Hamiltonian at high-symmetry points in the first Brillouin zone. An explanation is proposed for several experimental results. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369166
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  • 6
    Electronic Resource
    Electronic Resource
    Textured Pb(Mg〈sub〉1/3〈/sub〉Nb〈sub〉2/3〈/sub〉)O〈sub〉3〈/sub〉-PbTiO〈sub〉3〈/sub〉 Ceramics by Templated Grain Growth (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 280-283 (Feb. 2007), p. 181-184 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Fiber textured 0.70PMN-0.30PT ceramics was fabricated using the Templated GrainGrowth (TGG) process. Tabular SrTiO3 particles synthesized in molten NaCl-KCl salts were used as templates and oriented in fine 0.70PMN-0.30PT matrix during rolling. Tabular SrTiO3 particles can stabilize in sintering by SPS technique and annealing. A degree of [001] texture (Lotgering factor ~ 0.38) was obtained by heteroepitaxial growth of oriented single PMN-PT on the SrTiO3 templateparticles
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/48/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.280-283.181.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    Resonant quantum coherence of magnetization at excited states in nanospin systems with different crystal symmetries (2000)
    Springer
    The European physical journal 16 (2000), S. 507-513 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 75.45.+j Macroscopic quantum phenomena in magnetic systems - 75.10.Jm Quantized spin models - 03.65.Bz Foundations, theory of measurement, miscellaneous theories (including Aharonov-Bohm effect, Bell inequalities, Berry's phase)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The quantum interference effects induced by the Wess-Zumino term, or Berry phase are studied theoretically in resonant quantum coherence of the magnetization vector between degenerate states in nanometer-scale single-domain ferromagnets in the absence of an external magnetic field. We consider the magnetocrystalline anisotropy with trigonal, tetragonal and hexagonal crystal symmetry, respectively. By applying the periodic instanton method in the spin-coherent-state path integral, we evaluate the low-lying tunnel splittings between degenerate excited states of neighboring wells. And the low-lying energy level spectrum of mth excited state are obtained with the help of the Bloch theorem in one-dimensional periodic potential. The energy level spectrum and the thermodynamic properties of magnetic tunneling states are found to depend significantly on the total spins of ferromagnets at sufficiently low temperatures. Possible relevance to experiments is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100510070210
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  • 8
    Electronic Resource
    Electronic Resource
    Topological phase interference effects in resonant quantum tunneling of the Néel vector between nonequivalent magnetic wells in mesoscopic single-domain antiferromagnets (2000)
    Springer
    The European physical journal 14 (2000), S. 349-361 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 03.65.Bz Foundations, theory of measurement, miscellaneous theories (including Aharonov-Bohm effect, Bell inequalities, Berry's phase) - 75.45.+j Macroscopic quantum phenomena in magnetic systems - 75.50.Ee Antiferromagnetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Resonant quantum tunneling of the Néel vector between nonequivalent magnetic wells is investigated theoretically for a nanometer-scale single-domain antiferromagnet with biaxial crystal symmetry in the presence of an external magnetic field applied along the easy anisotropy axis, based on the two-sublattice model. Both the Wentzel-Kramers-Brillouin exponent and the preexponential factors are evaluated in the instanton contribution to the tunneling rate for finite and zero magnetic fields by applying the instanton technique in the spin-coherent-state path-integral representation, respectively. The quantum interference or spin-parity effects induced by the topological phase term in the Euclidean action are discussed in the rate of quantum tunneling of the Néel vector. In the absence of an external applied magnetic field, the effect of destructive phase interference or topological quenching on resonant quantum tunneling of the Néel vector is evident for the half-integer excess spin antiferromagnetic nanoparticle. In the weak field limit, the tunneling rates are found to oscillate with the external applied magnetic field for both integer and half-integer excess spins. We discuss the experimental condition on the applied magnetic field which may allow one to observe the topological quenching effect for nanometer-scale single-domain antiferromagnets with half-integer excess spins. Tunneling behavior in resonant quantum tunneling of the magnetization vector between nonequivalent magnetic wells is also studied for a nanometer-scale single-domain ferromagnet by applying the similar technique, but in the large noncompensation limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100510050139
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  • 9
    Electronic Resource
    Electronic Resource
    Field-dependent quantum nucleation of antiferromagnetic bubbles (2000)
    Springer
    The European physical journal 18 (2000), S. 703-712 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 75.45.+j Macroscopic quantum phenomena in magnetic systems - 73.40.Gk Tunneling - 75.30.Gw Magnetic anisotropy - 75.50.Ee Antiferromagnetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The phenomenon of quantum nucleation is studied in a nanometer-scale antiferromagnet with biaxial symmetry in the presence of a magnetic field at an arbitrary angle. Within the instanton approach, we calculate the dependence of the rate of quantum nucleation and the crossover temperature on the orientation and strength of the field for bulk solids and two-dimensional films of antiferromagnets, respectively. Our results show that the rate of quantum nucleation and the crossover temperature from thermal-to-quantum transitions depend on the orientation and strength of the field distinctly, which can be tested with the use of existing experimental techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100510070018
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  • 10
    Electronic Resource
    Electronic Resource
    Structure and electronic properties of TI8C12 cluster (1993)
    Springer
    The European physical journal 27 (1993), S. 275-279 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. + d ; 31.20.Sy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Structure and electronic properties of recently discovered Ti8C12 molecule are studied using the discrete variational method within the framework of local density approximation. The geometry of this novel cluster is optimized to be a distorted dodecahedron by varing the bond lengths of Ti-C and C-C while maintaining theT h symmetry, and the electronic states and the chemical bonding are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01436544
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