Competing Orders in two-dimensional Bose-Fermi mixtures

TL;DR

This paper investigates the zero-temperature phase diagram of two-dimensional Bose-Fermi mixtures in optical lattices using a functional renormalization group approach, revealing competing pairing and magnetic orders.

Contribution

It introduces a detailed RG analysis of Bose-Fermi mixtures, highlighting the dominance of various pairing symmetries and magnetic phases near half-filling.

Findings

Spin-1/2 fermions exhibit competing s, p, d pairing and antiferromagnetic order.

Spinless fermions predominantly show p-wave pairing.

Gaps and subdominant orders are quantitatively characterized.

Abstract

Using a functional renormalization group approach we study the zero temperature phase diagram of two-dimensional Bose-Fermi mixtures of ultra-cold atoms in optical lattices, in the limit when the velocity of bosonic condensate fluctuations are much larger than the Fermi velocity. For spin-1/2 fermions we obtain a phase diagram, which shows a competition of pairing phases of various orbital symmetry ($s$, $p$, and $d$) and antiferromagnetic order. We determine the value of the gaps of various phases close to half-filling, and identify subdominant orders as well as short-range fluctuations from the RG flow. For spinless fermions we find that p-wave pairing dominates the phase diagram.