Impurity-induced double transitions for accidentally degenerate unconventional pairing states

Abstract

Nonmagnetic impurities can lift the accidental degeneracy of unconventional pairing states, such as the (d+ig)-wave state recently proposed for Sr2RuO4. This type of effect would lead to a superconducting double transition upon impurity doping. In a model calculation it is shown how this behavior depends on material parameters and how it could be detected.