Itinerant ferromagnetism in an ultracold atom fermi gas

Phys Rev Lett. 2005 Dec 2;95(23):230403. doi: 10.1103/PhysRevLett.95.230403. Epub 2005 Nov 29.

Abstract

We address the possible occurrence of ultracold atom ferromagnetism by evaluating the free energy of a spin polarized Fermi gas to second order in its interaction parameter. We find that Hartree-Fock theory underestimates the tendency toward ferromagnetism, predict that the ferromagnetic transition is first order at low temperatures, and point out that the spin coherence time of gases prepared in a ferromagnetic state is strongly enhanced as the transition is approached. We relate our results to recent experiments.