J. K. Block, N. T. Zinner, G. M. Bruun
We consider the density wave instability of fermionic dipoles aligned by an external field, and moving in equidistant layers at zero temperature. Using a conserving Hartree-Fock approximation, we calculate the critical coupling strength for the formation of density waves as a function of the dipole orientation and the distance between the layers and also consider the effect of a non-zero layer width. We find that exchange correlations within each layer suppress the density wave instability significantly. Conversely, interactions between dipoles in different layers enhance the density wave instability. This effect, which is strongest when the dipoles are oriented perpendicular to the planes, causes the density waves in neighboring layers to be in-phase for all orientations of the dipoles. We demonstrate that the effects of the interlayer interaction can be understood from a simple classical model.
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http://arxiv.org/abs/1204.1822
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