The ab initio study of unconventional superconductivity in CeCoIn$_{5}$ and FeSe

TL;DR

This paper introduces a new ab initio method to evaluate Cooper pair susceptibility using Wannier orbitals, applied to CeCoIn$_{5}$ and FeSe, revealing potential FFLO superconducting phases at finite magnetic fields.

Contribution

The paper presents an efficient ab initio approach to study unconventional superconductivity, specifically the FFLO phase, in complex materials using Wannier orbitals.

Findings

FFLO phase likely occurs at finite magnetic field in CeCoIn$_{5}$.

FFLO phase likely occurs at finite magnetic field in FeSe.

Method enables exploration of superconducting instabilities from first principles.

Abstract

Electronic structure and the shape of the Fermi surface are known to be of fundamental importance for the superconducting instability in real materials. We demonstrate that such an instability may be explored by static Cooper pair susceptibility renormalized by pairing interaction and present an efficient method of its evaluation using Wannier orbitals derived from ab initio calculation. As an example, this approach is used to search for an unconventional superconducting phase of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) type in a heavy-fermion compound CeCoIn$_5$ and an iron-based superconductor FeSe. The results suggest that the FFLO superconducting phase occurs at finite magnetic field in both materials.