Itinerant Ferromagnetism in ultracold Fermi gases

TL;DR

This paper investigates itinerant ferromagnetism in ultracold Fermi gases with repulsive interactions, using a generalized Jastrow-Slater approach to analyze phase transitions, thermodynamics, and collective behaviors.

Contribution

It introduces a generalized Jastrow-Slater approximation for finite polarization and temperature, providing new insights into ferromagnetic phase transitions and collective modes in ultracold Fermi gases.

Findings

Second order transition at $ak_F\simeq0.90$ consistent with QMC

Calculated thermodynamic functions and fluctuations

Predicted collective modes and tri-critical points

Abstract

Itinerant ferromagnetism in cold Fermi gases with repulsive interactions is studied applying the Jastrow-Slater approximation generalized to finite polarization and temperature. For two components at zero temperature a second order transition is found at $ak_F\simeq0.90$ compatible with QMC. Thermodynamic functions and observables such as the compressibility and spin susceptibility and the resulting fluctuations in number and spin are calculated. For trapped gases the resulting cloud radii and kinetic energies are calculated and compared to recent experiments. Spin polarized systems are recommended for effective separation of large ferromagnetic domains. Collective modes are predicted and tri-critical points are calculated for multi-component systems.