Mixed-parity superconductivity near Lifshitz transitions in strongly spin-orbit-coupled metals

TL;DR

This paper investigates how strong spin-orbit coupling near Lifshitz transitions can induce mixed-parity superconductivity with helical triplet components in metals, using renormalization group analysis of a Hubbard model.

Contribution

It demonstrates that metals close to Lifshitz transitions with strong Rashba spin-orbit coupling are inherently prone to forming mixed-parity superconducting states.

Findings

Predominance of mixed-parity superconductivity near Lifshitz points

Identification of helical triplet components in the superconducting state

Application of renormalization group analysis to strongly spin-orbit-coupled systems

Abstract

We consider a strongly spin-orbit-coupled metal, one of whose Fermi surfaces is close to a Lifshitz (topological) transition. Via a renormalization group analysis of the square-lattice Hubbard model with strong Rashba spin-orbit coupling, we show that such a metal is generically unstable to the formation of mixed-parity superconductivity with a helical triplet component.