Density of states and order parameter in dirty anisotropic superconductors

Pokrovsky, S. V.; Pokrovsky, V. L.

doi:10.1103/physrevb.54.13275

Cited by 33 publications

(46 citation statements)

References 32 publications

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“…For H c, solving two linear equations (32) and (55) expresses D 1 and D 2 in terms of observed H ′ c2 and ρ n :…”

Section: Discussionmentioning

confidence: 99%

“…Indeed, if the intraband scattering is dominated by impurities (like C or N) which mostly reduce D 1 in the main σ-band, (D 1 ≪ D 1 ), then, according to Eqs. (32) and (33), the ratio H || c2 /H ⊥ c2 is minimum at T c and increases as T decreases. This behavior has indeed been observed on many, mostly clean, M gB 2 samples 11,12,13,14,15,16,17,18,19,20,21 .…”

Section: B Temperature Dependence Of the Anisotropy Of Hc2mentioning

confidence: 99%

“…The effect of interband scattering on T c suppression was considered before 32,33,35 APPENDIX C: MATRIX M Inserting Eq. (44) into the gap equation (4) yields…”

Section: Appendix A: Derivation Of the Uzadel Equationsmentioning

confidence: 99%

“…The theory of the two-band superconductivity has been developed long ago 31 , and more recently generalized to include the effects of impurities 32,33,34,35,36,37 and strong electron-phonon coupling 2,36,37,38 . The Fermi surface of M gB 2 provides three different impurity scattering channels: intraband scattering within each σ and π FS sheets and interband scattering between them.…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of the upper critical field by nonmagnetic impurities in dirty two-gap superconductors

2003

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Quasiclassic Uzadel equations for two-band superconductors in the dirty limit with the account of both intraband and interband scattering by nonmagnetic impurities are derived for any anisotropic Fermi surface. From these equations the Ginzburg-Landau equations, and the critical temperature Tc are obtained. An equation for the upper critical field, which determines both the temperature dependence of Hc2(T ) and the orientational dependence of Hc2(θ) as a function of the angle θ between H and the c-axis is obtained. It is shown that the shape of the Hc2(T ) curve essentially depends on the ratio of the intraband electron diffusivities D1 and D1, and can be very different from the standard one-gap dirty limit theory. In particular, the value Hc2(0) can considerably exceed 0.7TcdHc2/dTc, which can have important consequences for applications of M gB2. A scaling relation is proposed which enables one to obtain the angular dependence of Hc2(θ) from the equation for Hc2 at H c. It is shown that, depending on the relation between D1 and D2, the ratio of the upper critical field H c2 /H ⊥ c2 for H ab and H ⊥ ab can both increase and decrease as the temperature decreases. Implications of the obtained results for M gB2 are discussed.

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“…For H c, solving two linear equations (32) and (55) expresses D 1 and D 2 in terms of observed H ′ c2 and ρ n :…”

Section: Discussionmentioning

confidence: 99%

Section: B Temperature Dependence Of the Anisotropy Of Hc2mentioning

confidence: 99%

“…The effect of interband scattering on T c suppression was considered before 32,33,35 APPENDIX C: MATRIX M Inserting Eq. (44) into the gap equation (4) yields…”

Section: Appendix A: Derivation Of the Uzadel Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enhancement of the upper critical field by nonmagnetic impurities in dirty two-gap superconductors

2003

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“…For this purpose we need corresponding formulae for a general dirty anisotropic superconductor. Such equations were derived in 4 . We reproduce them here for readers convenience and because there occurred several misprints in the cited work which we correct here.…”

Section: Introductionmentioning

confidence: 99%

Specific-heat discontinuity in impure two-band superconductors

et al. 2003

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The Ginzburg-Landau coefficients, and the jump of the specific heat are calculated for a disordered two-band superconductor. We start with the analysis of a more general case arbitrary anisotropy. While the specific heat discontinuity at the critical temperature Tc decreases with increasing disorder, its ratio to the normal state specific heat at Tc increases and slowly converges to the isotropic value. For a strong disorder the deviation from the isotropic value is proportional to the elastic electron scattering time. In the case of a two-band superconductor we apply a simplified model of the interaction independent on momentum within a band. In the framework of this model all thermodynamic values can be found explicitly at any value of the scattering rate. This solution explains the sample dependence of the specific heat discontinuity in MgB2 and the influence of the disorder on the critical temperature.

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Van Hove Singularity and Superconductivity in a Disordered Hubbard Model

Litak

2002

phys. stat. sol. (b)

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Subject classification: 74.62.Dh We apply the Coherent Potential Approximation (CPA) to a simple extended Hubbard model with a nearest and next nearest neighbour hopping for disordered superconductors with s-, d-and p-wave pairing. We show how the Van Hove singularities in the electron density of states enhance the transition temperature T c for exotic superconductors in a clean and weakly disordered system. The Anderson theorem and the pair-breaking effects in presence of the Van Hove singularity caused by non-magnetic disorder are also discussed.

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Density of states and order parameter in dirty anisotropic superconductors

Cited by 33 publications

References 32 publications

Enhancement of the upper critical field by nonmagnetic impurities in dirty two-gap superconductors

Enhancement of the upper critical field by nonmagnetic impurities in dirty two-gap superconductors

Specific-heat discontinuity in impure two-band superconductors

Van Hove Singularity and Superconductivity in a Disordered Hubbard Model

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