Itinerant ferromagnetism in an atomic Fermi gas: Influence of population imbalance

TL;DR

This paper studies how population imbalance affects ferromagnetic phase transitions in ultracold atomic Fermi gases, revealing a change from first to second order transition and identifying different phase behaviors in traps.

Contribution

It demonstrates the impact of population imbalance on the order of ferromagnetic transitions and characterizes phase behavior in trapped systems.

Findings

Transition order changes from first to second with imbalance

Identifies three phase behaviors in trapped gases

Discusses experimental implications

Abstract

We investigate ferromagnetic ordering in an itinerant ultracold atomic Fermi gas with repulsive interactions and population imbalance. In a spatially uniform system, we show that at zero temperature the transition to the itinerant magnetic phase transforms from first to second order with increasing population imbalance. Drawing on these results, we elucidate the phases present in a trapped geometry, finding three characteristic types of behavior with changing population imbalance. Finally, we outline the potential experimental implications of the findings.