Density instabilities in a two-dimensional dipolar Fermi gas |
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Authors: | Parish M M Marchetti F M |
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Institution: | Cavendish Laboratory, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom. mmp24@cam.ac.uk |
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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-Sj?lander 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. |
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