Fulde-Ferrell-Larkin-Ovchinnikov state in disordered s-wave superconductors

TL;DR

This paper investigates the stability and structure of the FFLO superconducting state in disordered two-dimensional s-wave superconductors using the Bogoliubov-de Gennes approach, revealing its resilience under moderate disorder and dependence on disorder configuration.

Contribution

It provides the first detailed analysis of how nonmagnetic impurities affect the spatial structure of FFLO states in 2D s-wave superconductors.

Findings

FFLO state survives under moderate disorder.

Order parameter remains approximately periodic with disorder.

Structure depends on Zeeman field, disorder strength, and configuration.

Abstract

The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state is a superconducting state stabilized by a large Zeeman splitting between up- and down-spin electrons in a singlet superconductor. In the absence of disorder, the superconducting order parameter has a periodic spatial structure, with periodicity determined by the Zeeman splitting. Using the Bogoliubov-de Gennes (BdG) approach, we investigate the spatial profiles of the order parameters of FFLO states in a two-dimensional s-wave superconductors with nonmagnetic impurities. The FFLO state is found to survive under moderate disorder strength, and the order parameter structure remains approximately periodic. The actual structure of the order parameter depends on not only the Zeeman field, but also the disorder strength and in particular the specific disorder configuration.