Dynamical spin-flip susceptibility for a strongly interacting ultracold Fermi gas

TL;DR

This paper investigates the dynamical spin-flip susceptibility in strongly interacting ultracold Fermi gases, revealing signatures of ferromagnetic transition through theoretical analysis and proposing experimental detection methods.

Contribution

It provides a theoretical study of the dynamical spin-flip susceptibility in ultracold Fermi gases, highlighting the emergence of a magnon peak as a signature of ferromagnetism.

Findings

Magnon peak appears in the spin-flip susceptibility at the ferromagnetic transition

The susceptibility signature can be observed via spin-dependent Bragg spectroscopy

The study uses the random-phase approximation to analyze dynamical properties

Abstract

The Stoner model predicts that a two-component Fermi gas at increasing repulsive interactions undergoes a ferromagnetic transition. Using the random-phase approximation we study the dynamical properties of the interacting Fermi gas. For an atomic Fermi gas under harmonic confinement we show that the transverse (spin-flip) dynamical susceptibility displays a clear signature of the ferromagnetic phase in a magnon peak emerging from the Stoner particle-hole continuum. The dynamical spin susceptibilities could be experimentally explored via spin-dependent Bragg spectroscopy.