Phase diagram of strongly attractive $p$-orbital fermions on optical lattices

TL;DR

This paper investigates the phase diagram of strongly attractive $p$-orbital fermions on a 2D lattice, revealing novel phases through perturbation theory, effective spin models, and mean-field analysis, with implications for cold-atom experiments.

Contribution

It introduces a detailed analysis of the phase diagram of $p$-orbital fermions under strong attraction, using perturbation theory and effective spin models, which is a novel approach in this context.

Findings

Identification of phase boundaries in the $p$-orbital fermion system.

Prediction of experimental signatures for different phases.

Development of an effective spin-Hamiltonian from the fermionic model.

Abstract

We examine a system of doubly degenerate $p$-orbital polarized fermions on a two-dimensional square lattice with a strong on-site interaction. We consider the system density at the half filling limit and tackle the strong attractive interaction using a perturbation theory. We treat the four-site square plaquette interaction term generated from the directional tunneling dependence of $p$-orbitals using the fourth order in perturbation theory. We map the strong coupling particle Hamiltonian into an effective spin-Hamiltonian and then use a variational mean field approach and a linear spin-wave theory to study the phase diagram. Further, we discuss the experimental signatures of these phases within the context of current cold-atom experimental techniques.