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  • 1
    Electronic Resource
    Electronic Resource
    Anisotropic transport scattering times for pure and dilute aluminium alloys (1975)
    Springer
    The European physical journal 19 (1975), S. 317-322 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The ideal transport scattering times for pure Al are calculated and found to be very anisotropic. The anisotropy is a sensitive function of temperature. It is due to the Fermi surface, the multi-plane-wave character of the electronic wavefunctions, the Umklapp processes, as well as the phonon spectrum. In addition, for a magnesium impurity in Al we have computed the residual transport scattering times as well as the quasiparticle lifetimes which we then compare. The scattering time anisotropy gives rise to deviations from Matthiessen's rule in dilute alloys.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01458879
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  • 2
    Electronic Resource
    Electronic Resource
    Spin Fluctuations in the Normal State Optical Conductivity (1999)
    Springer
    Journal of superconductivity 12 (1999), S. 667-673 
    Details
    ISSN: 1572-9605
    Keywords: A.C. conductivity ; spin fluctuations ; oxides ; spectral density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A theory is given for the structure present in the normal state optical conductivity that reflects the underlying spin fluctuations for a system in which the charge carriers interact through the antiferromagnetic spin susceptibility. Such an interaction involves strong momentum anisotropies and energy dependence that modulates the frequency dependence of the conductivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007756220115
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  • 3
    Electronic Resource
    Electronic Resource
    Coupling strength of charge carriers to spin fluctuations in high-temperature superconductors (1999)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 401 (1999), S. 354-356 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In conventional superconductors, the most direct evidence of the mechanism responsible for superconductivity comes from tunnelling experiments, which provide a clear picture of the underlying electron–phonon interactions. As the coherence length in conventional superconductors is large, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/43843
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  • 4
    Electronic Resource
    Electronic Resource
    Optical Conductivity in Orthorhombic d-Wave Superconductors (1999)
    Springer
    Journal of low temperature physics 115 (1999), S. 251-280 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The large anisotropies observed in the in-plane transport properties of untwinned single crystals of YBa 2 Cu 3 O 6.95 reside in the orthorhombic nature of its band structure which includes CuO chains as well as CuO 2 planes. An infinite band model with distinct effective mass in a and b-direction is used to study the a.c. conductivity of a d-wave BCS superconductor. A subdominant s-wave admixture is also included in the gap because both symmetries belong to the same irreducible representation in an orthorhombic system. Parameters are fit to experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021879520432
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  • 5
    Electronic Resource
    Electronic Resource
    On the critical temperature of anisotropic superconductors (1982)
    Springer
    Journal of low temperature physics 47 (1982), S. 157-167 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An approximate analytic formula for the increase in the superconducting critical temperature caused by anisotropy is derived and compared with both the results of exact numerical solutions of the Eliashberg equations and with a previous approximate formula due to Allen and Butler. In all the cases considered our new formula is found to be more accurate than the previous one and to agree reasonably well with the exact results for the intermediate and weak coupling superconductors considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00682025
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  • 6
    Electronic Resource
    Electronic Resource
    On the effective spectral densities for a superconductor with paramagnons (1984)
    Springer
    Journal of low temperature physics 57 (1984), S. 291-305 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Solutions of generalized Eliashberg equations containing an explicit paramagnon contribution are generated and used to obtain tunneling characteristics, which are then inverted in order to recover an effective spectral density. We consider several shapes for the paramagnon spectral density and vary the characteristic paramagnon energy. We invert the information on the gap using both the generalized and conventional Eliashberg equations and compare the effective spectral functions obtained by these methods with each other and with the actual kernels for the electron paramagnon and electron phonon spectral density. Scaling laws relating approximately the inverted and actual kernels are established and limitations on these laws described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00681194
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  • 7
    Electronic Resource
    Electronic Resource
    Thermodynamics of superconducting lanthanum (1983)
    Springer
    Journal of low temperature physics 51 (1983), S. 135-148 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have calculated the thermodynamics of superconducting lanthanum from numerical solutions of the finite-temperature Eliashberg equations, written on the imaginary frequency axis, with electron-phonon kernel taken from the available tunneling data. We compare the theory with a recent specific heat determination of the thermodynamics. Also, we study several possible changes in the spectral density chosen to improve agreement with experiment. Our favored spectrum is obtained by a constant scaling of the tunneling spectral density chosen to increase the mass enhancement parameter from 0.79 to approximately 1.0.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00683418
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  • 8
    Electronic Resource
    Electronic Resource
    On the critical temperature of strong coupling superconductors with paramagnetic impurities (1985)
    Springer
    Journal of low temperature physics 58 (1985), S. 451-465 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We calculate the effects of paramagnetic impurities on the critical temperature of several intermediate and strong coupling superconductors by numerically solving the Eliashberg equations, and compare the results with the results of Abrikosov-Gorkov theory. For all the superconductors considered, the values of critical impurity concentration obtained from this exact numerical calculation are found to be considerably larger than the values given by Abrikosov-Gorkov theory. By generalizing a previous work of Leavens and Carbotte, we derive simple analytical expressions for the critical temperature and the critical concentration that give results much closer to the exact values than the corresponding BCS values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00681137
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  • 9
    Electronic Resource
    Electronic Resource
    On the microscopic interaction in the Chevrel compounds Cu2Mo6S8 and Mo6Se8 (1986)
    Springer
    Journal of low temperature physics 63 (1986), S. 1-22 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The available data on the superconducting properties of Cu2Mo6S8 and Mo6Se8 are used to gain some insight into their microscopic parameters α2 F(ω) and μ*, the electron-photon spectral density and Coulomb pseudopotential, respectively. While thermodynamic data play a prominent role in the analysis, use is also made of information on the generalized phonon frequency distributionG(ω) and, for the case of Cu2Mo6S8, on the second derivative of current-voltage tunneling data. The parameters obtained are tested against upper critical magnetic field data. The work suggests that the electron mass enhancement parameter λ may be of order 2 with μ* unusually large.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00682061
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  • 10
    Electronic Resource
    Electronic Resource
    Detailed study of the thermodynamics of a superconductor with paramagnons (1981)
    Springer
    Journal of low temperature physics 42 (1981), S. 585-600 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: The effect of paramagnons on the thermodynamics of a superconductor has been studied within Eliashberg theory. For model microscopic parameters approximating those characteristic of Nb we compare results for finite and zero paramagnon mass enhancement parameter, λspin. The change obtained in the thermodynamics is significant, but because of present uncertainties in the experimental data and in the value of the calculated electron-phonon interaction, an accurate value of λspin cannot be determined. The effect of spin fluctuations on the quasiparticle density of states in the region of phonon energies is also investigated. Our results have implications for tunneling inversion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00117432
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