Itinerant chiral ferromagnetism in a trapped Rashba spin-orbit coupled Fermi gas

TL;DR

This paper investigates how Rashba spin-orbit coupling influences the emergence of itinerant ferromagnetism in a trapped Fermi gas, revealing a transition from ferromagnetic to correlated non-magnetic phases and identifying chiral currents as experimental signatures.

Contribution

It introduces a detailed analysis of ferromagnetic phase emergence in a Rashba spin-orbit coupled Fermi gas, highlighting the role of correlations and spin-orbit effects beyond mean-field theory.

Findings

Ferromagnetic phase appears at intermediate interactions.

Strong interactions favor a correlated non-magnetic phase.

Chiral current density is a signature of ferromagnetism.

Abstract

How ferromagnetic phases emerge in itinerant systems is an outstanding problem in quantum magnetism. Here we consider a repulsive two-component Fermi gas confined in a two dimensional isotropic harmonic potential and subject to a large Rashba spin-orbit (SO) coupling, whose single-particle dispersion can be tailored by adjusting the SO coupling strength. We show that the interplay among SO coupling, correlation effects and mean-field repulsion leads to a competition between ferromagnetic and non-magnetic phases. At intermediate interaction strengths, ferromagnetic phase emerges which can be well described by the mean-field Hartree-Fock theory; whereas at strong interaction strengths, a strongly correlated non-magnetic phase is favored due to the beyond-mean-field quantum correlation effects. Furthermore, the ferromagnetic phase of this system possesses a chiral current density induced by the Rashba spin-orbit coupling, whose experimental signature is investigated.