Effects of impurities on superconductivity in noncentrosymmetric compounds

TL;DR

This paper derives a microscopic Ginzburg-Landau theory for noncentrosymmetric superconductors with spin-orbit coupling, analyzing how nonmagnetic impurities affect critical temperature and upper critical field, revealing disorder's complex influence.

Contribution

It provides a detailed theoretical framework for understanding impurity effects on superconductivity in noncentrosymmetric materials, including both conventional and unconventional pairing.

Findings

Disorder suppresses critical temperature for both pairing types.

Impurity effects on upper critical field depend on pairing symmetry and band structure.

In BCS-like models, Tc remains unchanged while Hc2 increases with disorder.

Abstract

We microscopically derive the Ginzburg-Landau free energy functional for a noncentrosymmetric superconductor with a large spin-orbit splitting of the electron bands, in the presence of nonmagnetic impurities. The critical temperature is found to be suppressed by disorder, both for conventional and unconventional pairing, in the latter case according to the universal Abrikosov-Gor'kov function. The impurity effect on the upper critical field turns out to be nonuniversal, determined by the pairing symmetry and the band structure. In a BCS-like model, Tc is not affected, while Hc2 increases with disorder. For unconventional pairing, both Tc and Hc2 are suppressed by disorder.