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arXiv · 1206.6797

Correlated Phases of Population Imbalanced Fermi-Fermi Mixtures on an Optical Lattice

Chen-Yen Lai·Chuntai Shi·Shan-Wen Tsai
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Abstract

We study a two species fermion mixture with different populations on a square lattice modeled by a Hubbard Hamiltonian with on-site inter-species repulsive interaction. Such a model can be realized in a cold atom system with fermionic atoms in two different hyperfine states loaded on an optical lattice and with tunable inter-species interaction strength via external fields. For a two-dimensional square lattice, when at least one of the fermion species is close to half-filling, the system is highly affected by lattice effects. With the majority species near half-filling and varying densities for the minority species, we find that several correlated phases emerge as the ground state, including a spin density wave state, a charge density wave state with stripe structure, and various p-wave BCS pairing states for both species. We study this system using a functional renormalization group method, determine its phase diagram at weak coupling, discuss the origin and characteristics of each phase, and provide estimates for the critical temperatures.

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Chen-Yen Lai, Chuntai Shi, Shan-Wen Tsai. 2013-01-24. Correlated Phases of Population Imbalanced Fermi-Fermi Mixtures on an Optical Lattice. https://doi.org/10.1103/physrevb.87.075134

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