Supersolid Bose-Fermi Mixtures in Optical Lattices

TL;DR

This paper investigates a mixture of strongly interacting bosons and spinless fermions in a 3D optical lattice, revealing phases like supersolids, localized bosons, and phase separation using a generalized DMFT approach.

Contribution

It develops a generalized DMFT scheme to accurately study Bose-Fermi mixtures across interaction strengths, focusing on half filling in three dimensions.

Findings

Supersolid phase with coexisting superfluidity and charge order at weak coupling.

Boson localization and persistent charge order at strong interspecies repulsion.

System exhibits phase separation tendency at weak boson-boson repulsion.

Abstract

We study a mixture of strongly interacting bosons and spinless fermions with on-site repulsion in a three-dimensional optical lattice. For this purpose we develop and apply a generalized DMFT scheme, which is exact in infinite dimensions and reliably describes the full range from weak to strong coupling. We restrict ourselves to half filling. For weak Bose-Fermi repulsion a supersolid forms, in which bosonic superfluidity coexists with charge-density wave order. For stronger interspecies repulsion the bosons become localized while the charge density wave order persists. The system is unstable against phase separation for weak repulsion among the bosons.