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Spin-charge-density wave in a rounded-square Fermi surface for ultracold atoms

TitleSpin-charge-density wave in a rounded-square Fermi surface for ultracold atoms
Publication TypeJournal Article
Year of Publication2012
AuthorsD. Makogon, I. B. Spielman, and C. Morais Smith
Date Publishedfeb
Keywords2012, Single Fellow

We derive and discuss an experimentally realistic model describing ultracold atoms in an optical lattice including a commensurate, but staggered, spin-flip term. The resulting band structure is quite exotic; fermions in the third band have an unusual rounded picture-frame Fermi surface (essentially two concentric squircles), leading to imperfect nesting. We develop a generalized theory describing the spin and charge degrees of freedom simultaneously at the random-field-approximation level, and show that the system can develop a coupled spin-charge-density wave order. Our generic approach can be used to study spin and charge instabilities in many materials, such as high- T c superconductors, organic compounds, graphene, and iron pnictides.