Theory for Magnetism and Triplet Superconductivity in LiFeAs

TL;DR

This paper develops a theoretical model for LiFeAs, showing that due to poor nesting and shallow pockets, it lacks antiferromagnetic order and instead exhibits ferromagnetic fluctuations leading to spin-triplet p-wave superconductivity.

Contribution

The study introduces a new theoretical framework for LiFeAs that explains its unique magnetic and superconducting properties compared to other pnictides.

Findings

Absence of antiferromagnetic order in LiFeAs

Presence of ferromagnetic fluctuations

Potential for spin-triplet p-wave superconductivity

Abstract

Superconducting pnictides are widely found to feature spin-singlet pairing in the vicinity of an antiferromagnetic phase, for which nesting between electron and hole Fermi surfaces is crucial. LiFeAs differs from the other pnictides by (i) poor nesting properties and (ii) unusually shallow hole pockets. Investigating magnetic and pairing instabilities in an electronic model that incorporates these differences, we find antiferromagnetic order to be absent. Instead we observe almost ferromagnetic fluctuations which drive an instability toward spin-triplet p-wave superconductivity.