Antiferromagnetism in a bosonic mixture of rubidium ($^{87}$Rb) and potassium ($^{41}$K)

TL;DR

This paper explores the potential to observe antiferromagnetic order in a two-dimensional optical lattice with a bosonic mixture of rubidium and potassium, highlighting how tuning interactions and lattice parameters can induce different quantum phases.

Contribution

It demonstrates, through mean-field simulations, the possibility of realizing antiferromagnetic order in a $^{87}$Rb-$^{41}$K mixture under experimentally feasible conditions.

Findings

Coexistence of Mott and AF phases for Rb atoms.

K atoms can remain in AF-superfluid phase.

Tuning interactions induces phase transitions.

Abstract

We simulate the experimental possibility of observing the antiferromagnetic (AF) order in the bosonic mixtures of rubidium ($^{87}$Rb) and potassium ($^{41}$K) in a two-dimensional optical lattice in the presence of harmonic confinement. By tuning the interspecies interactions and the lattice heights we have found the ground states, within the mean-field approximation, that interpolate from the phase separation to the AF order. For a moderate lattice height the coexistence of the Mott and AF phase is possible for the Rb atoms while the K atoms remain in the AF-superfluid phase. This observation may provide an experimental feasibility to hitherto unobserved AF order for $^{87}$Rb - $^{41}$K mixture.