Realizing Altermagnetism in Fermi-Hubbard Models with Ultracold Atoms

TL;DR

This paper proposes a theoretical method to realize and detect altermagnetism, a novel collinear magnetic phase with spin-split bands, using ultracold fermionic atoms in optical lattices, expanding the understanding of magnetic phases.

Contribution

It introduces an altermagnetic Hubbard model with anisotropic hopping and demonstrates the phase diagram and experimental signatures for ultracold atom systems.

Findings

Altermagnetic phase can be realized with ultracold atoms in optical lattices.

The phase diagram includes metallic and insulating altermagnetic phases.

Anisotropic spin transport can be experimentally detected.

Abstract

Altermagnetism represents a type of collinear magnetism, that is in some aspects distinct from ferromagnetism and from conventional antiferromagnetism. In contrast to the latter, sublattices of opposite spin are related by spatial rotations and not only by translations and inversions. As a result, altermagnets have spin-split bands leading to unique experimental signatures. Here, we show theoretically how a d-wave altermagnetic phase can be realized with ultracold fermionic atoms in optical lattices. We propose an altermagnetic Hubbard model with anisotropic next-nearest neighbor hopping and obtain the Hartree-Fock phase diagram. The altermagnetic phase separates in a metallic and an insulating phase and is robust over a large parameter regime. We show that one of the defining characteristics of altermagnetism, the anisotropic spin transport, can be probed with trap-expansion experiments.