Local tunneling spectroscopy as signatures of the Fulde-Ferrell-Larkin-Ovchinnikov state in s- and d-wave Superconductors

TL;DR

This study investigates the local tunneling spectroscopy signatures of FFLO states in two-dimensional s- and d-wave superconductors under magnetic fields, revealing distinctive LDOS patterns that can identify these exotic states.

Contribution

It provides a self-consistent analysis of FFLO states in s- and d-wave superconductors, highlighting unique local density of states features and spatial patterns as potential experimental signatures.

Findings

Stripe order in s-wave superconductors has lower free energy.

Square lattice order is favored in d-wave superconductors.

LDOS exhibits bias-dependent checkerboard patterns in d-wave cases.

Abstract

The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states for two-dimensional s- and d-wave superconductors (s- and d-SC) are self-consistently studied under an in-plane magnetic field. While the stripe solution of the order parameter (OP) is found to have lower free energy in s-SC, a square lattice solution appears to be energetically more favorable in the case of d-SC. At certain symmetric sites, we find that the features in the local density of states (LDOS) can be ascribed to two types of bound states. We also show that the LDOS maps for d-SC exhibit bias-energy-dependent checkerboard patterns. These characteristics can serve as signatures of the FFLO states.