title: Density instabilities in a two-dimensional dipolar Fermi gas.
abstract: We study the density instabilities of a two-dimensional gas of dipolar fermions with aligned dipole moments. The random phase approximation (RPA) for the density-density response function is never accurate for the dipolar gas, and so we incorporate correlations beyond RPA via an improved version of the Singwi-Tosi-Land-Sjölander scheme. In addition to density-wave instabilities, our formalism captures the collapse instability that is expected from Hartree-Fock calculations but is absent from RPA. Crucially, we find that when the dipoles are perpendicular to the layer, the system spontaneously breaks rotational symmetry and forms a stripe phase, in defiance of conventional wisdom.
authors.affiliation: Cavendish Laboratory, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom. mmp24@cam.ac.uk
authors.forename: M M
authors.initials: MM
authors.lastname: Parish
authors.forename: F M
authors.initials: FM
authors.lastname: Marchetti