# Unified description of dynamics of a repulsive two-component Fermi gas

## TL;DR

This paper investigates the dynamics of a two-component Fermi gas, revealing a ferromagnetic transition driven by increasing repulsive interactions, supported by both theoretical models and experimental agreement.

## Contribution

It provides a unified theoretical description of the spin-dipole oscillations and ferromagnetic instability in a repulsive Fermi gas, aligning with recent experimental findings.

## Key findings

- Identification of ferromagnetic transition with increasing interaction strength
- Observation of spin-dipole mode softening before ferromagnetism
- Agreement between theoretical models and experimental data

## Abstract

We study a binary spin-mixture of a zero-temperature repulsively interacting $^6$Li atoms using both the atomic-orbital and the density functional approaches. The gas is initially prepared in a configuration of two magnetic domains and we determine the frequency of the spin-dipole oscillations which are emerging after the repulsive barrier, initially separating the domains, is removed. We find, in agreement with recent experiment (G. Valtolina et al., arXiv:1605.07850 (2016)), the occurrence of a ferromagnetic instability in an atomic gas while the interaction strength between different spin states is increased, after which the system becomes ferromagnetic. The ferromagnetic instability is preceded by the softening of the spin-dipole mode.