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arXiv · 0902.0388

Dispersive spectrum and orbital order of spinless p-band fermions in an optical lattice

Xiancong Lu·E. Arrigoni
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Abstract

We study single-particle properties of a spinless p-band correlated fermionic gas in an optical lattice by means of a variational cluster approach (VCA). The single-particle spectral function is almost flat at half-filling and develops a strongly dispersive behavior at lower fillings. The competition between different orbital orderings is studied as a function of filling. We observe that an ``antiferromagnetic'' orbital order develops at half-filling and is destroyed by doping the system evolving into a disordered orbital state. At low filling limit, we discuss the possibility of ``ferromagnetic'' orbital order by complementing the VCA result with observations based on a trial wave function. We also study the behavior of the momentum distribution for different values of the on-site interaction. Finally, we introduce an integration contour in the complex plane which allows to efficiently carry out Matsubara-frequency sums.

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Xiancong Lu, E. Arrigoni. 2009-06-22. Dispersive spectrum and orbital order of spinless p-band fermions in an optical lattice. https://doi.org/10.1103/physrevb.79.245109

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