Antiferromagnetic Order in a Spin-Orbit Coupled Bose-Einstein Condensate

TL;DR

This paper investigates how spin-orbit coupling in a Bose-Einstein condensate within a 2D optical lattice leads to antiferromagnetic order, revealing new quantum magnetic phenomena and phase interplay.

Contribution

It demonstrates the emergence of antiferromagnetic order in a spin-orbit coupled BEC, highlighting the ground state's degeneracy and magnetic properties in a cold atom system.

Findings

Ground state favors coherent condensate over fragmented one

Large degeneracy in the ground state

Emergence of antiferromagnetic order under certain conditions

Abstract

Spin-orbit coupling related new physics and quantum magnetism are two branches of great interest both in condensed matter physics and in cold atomic physics. With the introduction of a Rashba-like SOC into a Bose-Einstein condensate (BEC) loaded in a two-dimensional bipartite optical square lattice, we find that the ground state of the BEC always favors a coherent condensate than a fragmented condensate and always exhibits very large degeneracy, and most importantly, an antiferromagnetic order of quantum nature emerges when parameters satisfy certain condition. This provides an ideal platform to study the interplay of antiferromagnetic phase and superfluid phase.