Mott insulators of ultracold fermionic alkaline earth atoms in three dimensions

TL;DR

This paper investigates the phase diagram of SU(N) Heisenberg models for Mott insulators of ultracold alkaline earth atoms in three dimensions, revealing various symmetry-breaking ground states including chiral spin liquids.

Contribution

It introduces a large-N solvable model to explore non-magnetic ground states and uncovers novel phases with lattice and time-reversal symmetry breaking.

Findings

Rich phase diagram with multiple symmetry-breaking states

Discovery of a bilayer chiral spin liquid phase

Lattice symmetry can spontaneously break into bilayers

Abstract

We study a class of SU(N) Heisenberg models, describing Mott insulators of fermionic ultra-cold alkaline earth atoms on the three-dimensional simple cubic lattice. Based on an earlier semiclassical analysis, magnetic order is unlikely, and we focus instead on a solvable large-N limit designed to address the competition among non-magnetic ground states. We find a rich phase diagram as a function of the filling parameter k, composed of a variety of ground states spontaneously breaking lattice symmetries, and in some cases also time reversal symmetry. One particularly striking example is a state spontaneously breaking lattice rotation symmetry, where the cubic lattice breaks up into bilayers, each of which forms a two-dimensional chiral spin liquid state.