Impurities in two band model of superconductor order parameter anisotropy

Arseev, P. I.; Fedorov, N. K.; Loiko, S. O.

doi:10.1016/s0038-1098(02)00521-5

Cited by 9 publications

(7 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the s-wave pairing and the s-wave impurity scattering, ζ (+) = 0, while ζ (−) = 1/τ 1AB . Thus, T c of the state with ∆ As = ∆ Bs is not suppressed by impurity doping at all, while that of the state with ∆ As = −∆ Bs is strongly suppressed, which is consistent with the results by Golubov and Mazin 6) and Arseev et al 7) When T c (+) < T c (−) , the alternation of the solution and thus the jump of α occurs.…”

supporting

confidence: 90%

Internal Transition of Superconducting State by Impurity Doping with a Jump of Isotope-effect Coefficient in Multiband Superconductors

Seki

2003

J. Phys. Soc. Jpn.

View full text Add to dashboard Cite

The impurity effects on the transition temperature Tc and the isotope effect are examined in multiband superconductors with magnetic and nonmagnetic impurities, where the effect of Coulomb repulsion is considered. It is shown that an internal transition of the superconducting state is induced by impurity doping, and that the transition is accompanied by a jump of the isotope-effect coefficient α. In particular, the transition is illustrated in a system with two electron bands. In some special cases, extended Abrikosov and Gor'kov (AG) equations for Tc and the expressions of the isotope-effect coefficient α are obtained. Possible relevance of the present mechanism to the experimental results of Sr2RuO4 is discussed.KEYWORDS: Abrikosov-Gor'kov equation, superconducting transition temperature, isotope effect, multiband superconductor, impurity effect, weakly screened electron-phonon interactionThe isotope-effect coefficient provides important information on the mechanism of superconductivity. For example, the BCS theory based on the electron-phonon interactions is supported in nontransition-metal superconductors, such as Hg and Zn, by their isotope-effect coefficient α, which is nearly equal to 0.5. In transition metals and some compounds, large deviations from α = 0.5 have been observed, but the deviations can be explained in the context of electron-phonon interactions by taking into account strong Coulomb repulsion, anharmonicity of lattice vibrations, and van Hove singularity. 1)On the other hand, in exotic superconductors, such as high-T c cuprates, organic superconductors, Sr 2 RuO 4 , and heavy fermion superconductors, nonphonon mechanisms of superconductivity, such as spin-fluctuation exchange interactions, have been examined as possible mechanisms. In such nonphonon mechanisms, the isotope-effect coefficient must deviate from 0.5 markedly, or vanish completely. The presence of the isotope shift (α = 0) suggests the presence of a contribution to the pairing interaction from electron-phonon interactions.Therefore, it may be difficult to derive information on the pairing mechanism solely from a single value of α. Therefore, it is useful to systematically examine correlations between α and other quantities, such as impurity concentration, transition temperature, hole concentration (for high-T c cuprates), and pressure.We examine the impurity effect on the isotope effect in this study. First, we briefly review it in single-band systems. In the presence of impurities, T c is reduced except for nonmagnetic isotropic impurity scattering and isotropic pairing. The ratio T c /T c0 satisfies the Abrikosov and Gor'kov (AG) equation 2)ln T c0

show abstract

supporting

confidence: 90%

Internal Transition of Superconducting State by Impurity Doping with a Jump of Isotope-effect Coefficient in Multiband Superconductors

Seki

2003

J. Phys. Soc. Jpn.

View full text Add to dashboard Cite

show abstract

“…Mg content the inplane a-axis lattice parameter decreases while the inter plane c-axis It is known that the inclusion of impurity in MgB 2 lattice reduces the T c of the sample [36][37][38] due to scattering effects [39][40][41]. Here, though sample M1 consists of Mg as depicted in XRD, the transition temperature observed is not reduced and is quite sharp.…”

Section: Resultsmentioning

confidence: 87%

Synthesis and characterization of excess magnesium MgB2 superconductor under inert carbon environment

Sinha¹,

Kadam²,

Mudgel³

et al. 2010

Physica C: Superconductivity

View full text Add to dashboard Cite

show abstract

“…For example, T c in conventional superconductors with the s-wave gap is insensitive to the nonmagnetic disorder and decreases rapidly with the increasing number of magnetic impurities [1,2]. On the contrary, the unconventional sign-changing d-wave gap in the high-T c cuprates and s ± gap in the iron-based superconductors leads to the suppression of the critical temperature by scattering on the nonmagnetic impurities [3,4,5,6,7,8,9]. Even more fascinating is the possibility to change the gap structure of multiband superconductors by the disorder.…”

Section: Introductionmentioning

confidence: 99%

Decisive proofs of the $s_\pm \to s_{++}$ transition in the temperature dependence of the magnetic penetration depth

Shestakov,

Korshunov,

Togushova

et al. 2021

Preprint

View full text Add to dashboard Cite

One of the features of the unconventional s ± state in iron-based superconductors is possibility to transform to the s ++ state with the increase of the nonmagnetic disorder. Detection of such a transition would prove the existence of the s ± state. Here we study the temperature dependence of the London magnetic penetration depth within the two-band model for the s ± and s ++ superconductors. By solving Eliashberg equations accounting for the spin-fluctuation mediated pairing and nonmagnetic impurities in the T -matrix approximation, we have derived a set of specific signatures of the s ± → s ++ transition: (1) sharp change in the behavior of the penetration depth λ L as a function of the impurity scattering rate at low temperatures; (2) before the transition, the slope of ∆λ L (T ) = λ L (T ) − λ L (0) increases as a function of temperature, and after the transition this value decreases; (3) the sharp jump in the inverse square of the penetration depth as a function of the impurity scattering rate, λ −2 L (Γa), at the transition; (4) change from the single-gap behavior in the vicinity of the transition to the two-gap behavior upon increase of the impurity scattering rate in the superfluid density ρs(T ).

show abstract

Impurities in two band model of superconductor order parameter anisotropy

Cited by 9 publications

References 22 publications

Internal Transition of Superconducting State by Impurity Doping with a Jump of Isotope-effect Coefficient in Multiband Superconductors

Internal Transition of Superconducting State by Impurity Doping with a Jump of Isotope-effect Coefficient in Multiband Superconductors

Synthesis and characterization of excess magnesium MgB2 superconductor under inert carbon environment

Decisive proofs of the $s_\pm \to s_{++}$ transition in the temperature dependence of the magnetic penetration depth

Contact Info

Product

Resources

About