title: Repulsive atomic gas in a harmonic trap on the border of itinerant ferromagnetism.
abstract: Alongside superfluidity, itinerant (Stoner) ferromagnetism remains one of the most well-characterized phases of correlated Fermi systems. A recent experiment has reported the first evidence for novel phase behavior on the repulsive side of the Feshbach resonance in a two-component ultracold Fermi gas. By adapting recent theoretical studies to the atomic trap geometry, we show that an adiabatic ferromagnetic transition would take place at a weaker interaction strength than is observed in experiment. This discrepancy motivates a simple nonequilibrium theory that takes account of the dynamics of magnetic defects and three-body losses. The formalism developed displays good quantitative agreement with experiment.
authors.affiliation: Cavendish Laboratory, 19, J.J. Thomson Avenue, Cambridge, CB3 0HE, United Kingdom. gjc29@cam.ac.uk
authors.forename: G J
authors.initials: GJ
authors.lastname: Conduit
authors.forename: B D
authors.initials: BD
authors.lastname: Simons