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  • 1
    Electronic Resource
    Electronic Resource
    Magnetic structures in colossal magnetoresistance perovskites (abstract) : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5487-5487 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ferromagnetism in colossal magnetoresistance perovskites such as LaxB1−xMnO3 (B=Ba, Sr, Ca) is typically explained using the double exchange (DE) mechanism proposed by Zener. To explain the local structure above Tc one needs to introduce a coupling to lattice degrees of freedom. Here, we show the structure of the resulting magnetoelastic polarons and the temperature dependence of their pair potential. To investigate the "ferro"-magnetic state below Tc we study the ferromagnetic Kondo lattice model in the strong coupling limit. It turns out that the DE mechanism has unexpected properties, when there is more than one itinerant electron. We find that in general, the many-body ground state of the DE model is not globally ferromagnetically ordered. Also, the low-energy excitations of this model are distinct from spin wave excitations in usual Heisenberg ferromagnets, which will result in unusual dynamic magnetic properties. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364575
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of the capacitive coupling of Josephson transmission lines (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1772-1776 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We study the capacitive coupling of two long Josephson junctions by imposing appropriate boundary conditions at the ends of the junctions. Numerical simulations show good agreement with analytical estimates of the parameter range for which reflections of fluxons at the coupled end of the junction occur. We discuss our results in terms of recent experiments concerning phase-locking phenomena in Josephson junctions fluxon oscillators devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344368
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  • 3
    Electronic Resource
    Electronic Resource
    Collective electronic oscillator/semiempirical calculations of static nonlinear polarizabilities in conjugated molecules (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 699-707 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The collective electronic oscillator (CEO) approach based on the time-dependent Hartree–Fock approximation is combined with INDO/S, MNDO, AM1, and PM3 semiempirical Hamiltonians. This technique is applied to compute and analyze the static nonlinear polarizabilities of a series of donor/acceptor substituted oligomers. To mimic the experimental conditions, polarizabilities in substituted molecules are calculated for the isolated complex and in a dielectric medium, wherein the solvent contributions are incorporated using the self-consistent reaction field approach. The dielectric environment significantly increases second and third order static polarizabilities and considerably improves the agreement with experimental data. We find that calculated spectroscopic observables agree well with experimental values. We conclude that the CEO/semiempirical approach is an inexpensive and numerically efficient method of computing nonlinear molecular properties. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1377035
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  • 4
    Electronic Resource
    Electronic Resource
    Strain-induced metal–insulator phase coexistence in perovskite manganites (2004)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 428 (2004), S. 401-404 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The coexistence of distinct metallic and insulating electronic phases within the same sample of a perovskite manganite, such as La1-x-yPryCaxMnO3, presents researchers with a tool for tuning the electronic properties in materials. In particular, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature02364
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  • 5
    Electronic Resource
    Electronic Resource
    Superconductivity fluctuations in a one-dimensional two-band electron-phonon model with strong repulsive interactions (1997)
    Springer
    Journal of experimental and theoretical physics 85 (1997), S. 163-167 
    Details
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study a one-dimensional, two-band model with short-range electron-electron repulsions (onsite U and nearest-neighbor V terms) and electron-phonon coupling. We show that there is a region of U, V and band filling in which singlet superconductivity fluctuations are dominant. This region is absent without electron-phonon interactions and includes large values of U and V.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.558300
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  • 6
    Electronic Resource
    Electronic Resource
    Isotopic Shifts in a Polaronic System (1999)
    Springer
    Journal of superconductivity 12 (1999), S. 37-39 
    Details
    ISSN: 1572-9605
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The effect of isotopic substitution in a model polaronic system is presented.We use a three-site many body electron–phonon model which includeselectronic correlations and electron–phonon interactions, showing thepresence of polaron tuneling for intermediate and strong couplings. Theisotopic substitution changes the dynamics of polaron tuneling. Additionallyin the intermediate electron–phonon coupling regime, relevant forhigh-T c superconductors, a change in the local structure is predicted. Inthis regime, the isotopic shift of phonon excitations is consistent withresults of optical measurements of c-axis phonons in YBa2Cu3O7.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007757200280
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  • 7
    Electronic Resource
    Electronic Resource
    Mesoscale Charge-Ordering in Transition Metal Oxides: Formation and Signatures (1999)
    Springer
    Journal of superconductivity 12 (1999), S. 209-213 
    Details
    ISSN: 1572-9605
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We briefly outline the value of an inhomogeneous (unrestricted) Hartree–Fock plus Random Phase approach for understanding the types and properties of mesoscopic patterns of localized small polarons in transition metal oxides. Using a multiband Peierls–Hubbard model for a hole-doped CuO2 layer as an illustrative example, we demonstrate the appearance of correlated high-energy (electronic) and low-energy (localized phonon and spin-wave) signatures of various vertical, diagonal, metal-centered, and oxygen-centered mesoscopic stripe patterns of localized holes (small polarons). This represents important inhomogeneous magneto-elastic coupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007735417544
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  • 8
    Electronic Resource
    Electronic Resource
    Lattice and Polarizability Effects on Singlet and Triplet States in an Effective Hamiltonian for High-Tc Cuprates (2000)
    Springer
    Journal of superconductivity 13 (2000), S. 491-496 
    Details
    ISSN: 1572-9605
    Keywords: electron-phonon injection ; superconductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract From various theoretical approaches it seems to be rather well established that the Zhang–Rice (ZR) singlet state should play an important role in doped high-temperature superconducting (HTSC) oxides. Yet the conclusion that a one-band model is capable of describing many of the unusual physics observed in HTSC compounds has been questioned because the p z states of the oxygen atoms in the planes as well as those of the apical oxygen atoms hybridize with the Cu d3z2-r2 orbitals and induce a mixing of the in-plane states with the out-of-plane bands. It is shown that electron–lattice coupling and polarizability effects modify the electronic structure of the effective Hamiltonian considered here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007727714453
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  • 9
    Electronic Resource
    Electronic Resource
    Local polarizability, structure, and charge-transfer in high-Tc superconductors (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 527-530 
    Details
    ISSN: 1572-9605
    Keywords: Polarizability ; polarons ; charge-transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Using 2-band Peierls-Hubbard cluster and chain models, we illustrate the importance of polarizability and coupled charge-lattice-spin effects in complex electronic materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00722847
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  • 10
    Electronic Resource
    Electronic Resource
    Comments on nonlinear excitations in the anisotropic Heisenberg chain (1980)
    Springer
    The European physical journal 37 (1980), S. 357-361 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is suggested that pulse soliton solutions for the classical, continuum, isotropic, ferromagnetic Heisenberg chain in a magnetic field continuously deform to sine Gordon breather solutions as anisotropy is increased to an extremeXY limit (theXY plane containing the applied field). The relevance of this observation for applications to magnetic chains such as CsNiF3 is emphasized, and comparisons with the zero-field limit are noted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01352747
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