Knight Shift in the FFLO State of a Two-Dimensional D-Wave Superconductor

TL;DR

This paper investigates the FFLO state in two-dimensional d-wave superconductors under high magnetic fields, revealing how the order parameter's spatial structure and Knight shift are affected, with implications for NMR experiments.

Contribution

It provides a self-consistent quasiclassical analysis of the FFLO state in 2D d-wave superconductors, highlighting the spatial symmetry breaking and node orientation effects.

Findings

FFLO state breaks translational symmetry along preferred directions

Node orientation in real space is pinned by momentum space basis function

Results have implications for interpreting NMR measurements in CeCoIn5

Abstract

We report on the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state in two-dimensional d-wave superconductors with magnetic field parallel to the superconducting planes. This state occurs at high magnetic field near the Pauli-Clogston limit and is a consequence of the competition between the pair condensation and Zeeman energy. We use the quasiclassical theory to self-consistently compute the spatially nonuniform order parameter. Our self-consistent calculations show that the FFLO state of a d-wave order parameter breaks translational symmetry along preferred directions. The orientation of the nodes in real space is pinned by the nodes of the basis function in momentum space. Here, we present results for the Knight shift and discuss the implications for recent nuclear magnetic resonance measurements on CeCoIn5.