Itinerant ferromagnetism in an ultracold atom fermi gas.
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.
Duine
R A
RA
Department of Physics, University of Texas at Austin, 1 University Station C1600, Austin, Texas 78712-0264, USA. duine@physics.utexas.edu
MacDonald
A H
AH