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

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.

arXiv comment5 pages, 4 figures, figures updated

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• Stable p-wave resonant two-dimensional Fermi-Bose dimers
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• p-wave Pairing in Two-Component Fermi System with Unequal Population: Weak Coupling BCS to Strong Coupling BEC Regimes
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• Phase diagram for the trapped p-wave fermionic superfluid with population imbalance
• d_{xy}-Density wave in fermion-fermion cold atom mixtures