Effects of Impurities with Singlet-Triplet Configuration on Multiband Superconductors

Abstract

Roles of multipole degrees of freedom in multiband superconductors are investigated in a case of impurities whose low-lying states consist of singlet ground and triplet excited states, which is related to the experimental fact that the transition temperature $T_{\mathrm{c}}$ is increased by Pr substitution for La in LaOs${}_4$Sb${}_{12}$. The most important contribution to the $T_{\mathrm{c}}$ increase comes from the inelastic interband scattering of electrons coupled to quadrupole or octupole moments of impurities. It is found that a magnetic field modifies an effective pairing interaction and the scattering anisotropy appears in the field-orientation dependence of the upper critical field $H_{\mathrm{c}2}$ in the vicinity of $T_{\mathrm{c}}$, although a uniaxial anisotropic field is required for experimental detection. This would be proof that the Pr internal degrees of freedom are relevant to the stability of superconductivity in (La${}_{1-x}$Pr${}_x$)Os${}_4$Sb${}_{12}$.

10 pages, 5 figures, to appear in J. Phys. Soc. Jpn

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• Effects of Impurities with Singlet-Triplet Configuration on Multiband Superconductors

Cited by in corpus (1)

• Effects of Impurities with Singlet-Triplet Configuration on Multiband Superconductors