Ferromagnetism of the Repulsive Atomic Fermi Gas: three-body recombination and domain formation

TL;DR

This paper demonstrates that a ferromagnetic phase can be stabilized in repulsive ultracold Fermi gases by using a moderate optical lattice, enabling experimental observation despite three-body recombination challenges.

Contribution

The study introduces a method to stabilize itinerant ferromagnetism in ultracold fermions with optical lattices, reducing recombination issues and enabling domain formation detection.

Findings

Ferromagnetic phase is stabilized at smaller scattering lengths with optical lattices.

Rapid formation of ferromagnetic domains from paramagnetic states.

Reduced three-body recombination allows experimental observation.

Abstract

The simplest model for itinerant ferromagnetism, the Stoner model, has so far eluded experimental observation in repulsive ultracold fermions due to rapid three-body recombination at large scattering lengths. Here we show that a ferromagnetic phase can be stabilised by imposing a moderate optical lattice. The reduced kinetic energy drop upon formation of a polarized phase in an optical lattice extends the ferromagnetic phase to smaller scattering lengths where three-body recombination is small enough to permit experimental detection of the phase. We also show, using time dependent density functional theory, that in such a setup ferromagnetic domains emerge rapidly from a paramagnetic initial state.