Antiferromagnetism with Ultracold Atoms

TL;DR

This paper demonstrates the realization of the Hubbard model with ultracold fermionic atoms and reports the observation of short-range antiferromagnetic order enabled by a novel cooling technique.

Contribution

The study introduces a compensated optical lattice method that achieves lower temperatures, allowing detection of antiferromagnetic correlations in a 3D optical lattice.

Findings

Formation of a Mott insulator at half-filling

Detection of short-range magnetic order via Bragg scattering

Development of a new cooling technique for ultracold atoms

Abstract

We use ultracold spin--1/2 atomic fermions ($^6$Li) to realize the Hubbard model on a three-dimensional (3D) optical lattice. At relatively high temperatures and at densities near half-filling, we show that the gas forms a Mott insulator with unordered spins. To observe antiferromagnetic order that is predicted to occur at lower temperatures, we developed the compensated optical lattice method to evaporatively cool atoms in the lattice. This cooling has enabled the detection of short-range magnetic order by spin-sensitive Bragg scattering of light.