Magnetism of cold fermionic atoms on the p band of an optical lattice

We carry out ab initio study of a ground state phase diagram of spin-1/2 cold fermionic atoms within a twofold degenerate p band of an anisotropic optical lattice. Using the Gutzwiller variational approach, we show that a robust ferromagnetic phase exists for a vast range of band fillings and interacting strengths. The ground state crosses over from a spin density wave state to a spin-1 Neel state at half filling. An additional harmonic trap will induce spatial separation of various phases. We also discuss several relevant observable consequences and detection methods. An experimental test of the results reported here may shed some light on the long-standing issue of itinerant ferromagnetism.