Impurity-induced configuration-transition in the Fulde-Ferrell-Larkin-Ovchinnikov state of a d-wave superconductor

TL;DR

This study explores how impurities and temperature influence the transition between 2D and 1D FFLO states in a d-wave superconductor, revealing impurity-induced configuration changes and the absence of the Fulde-Ferrell state.

Contribution

It demonstrates impurity and temperature effects on FFLO state configurations in d-wave superconductors using a tight-binding model and Bogoliubov-de Gennes equations.

Findings

Impurities distort the 2D FFLO order parameter locally.

Increasing impurity concentration favors a quasi-1D FFLO state.

Temperature increase can induce a 2D to 1D FFLO transition.

Abstract

The effect of impurities on Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states in a layered superconductor with d-wave pairing symmetry is investigated using the tight-binding model and the Bogoliubov-de Gennes equations. At low temperature and a strong exchange field applied parallel to its conducting plane, a two-dimensional (2D) square lattice-like Larkin-Ovchinnikov state is more energetically favorable in a clean system. In the presence of impurities, the spatial profile of the order parameter remains as a 2D square lattice, and it is distorted only near the impurities when the impurity concentration is low. As impurity concentration is increased to a certain level, quasi-one-dimensional (1D) like FFLO state becomes more energetically favorable. Increasing temperature with fixed impurity concentration can also induce a 2D to 1D FFLO state transition. Within the present finite size calculation, we did not find the existence of the Fulde and Ferrell state before the system becoming normal as the impurity concentration is raised.