Orbital magnetism of ultracold fermionic gases in a lattice: dynamical mean-field approach

TL;DR

This paper investigates how exchange interactions influence magnetic phases in ultracold fermionic gases in optical lattices using dynamical mean-field theory, providing phase diagrams and entropy estimates to guide experiments.

Contribution

It applies dynamical mean-field theory to analyze finite-temperature magnetic phases in a two-band Hubbard model with exchange interactions, offering new insights into experimental regimes for magnetic ordering.

Findings

Identifies conditions for ferromagnetic ordering in ultracold gases.

Provides phase diagrams including magnetic transitions.

Quantifies entropy near magnetic phases.

Abstract

We study finite-temperature properties of ultracold four-component mixtures of alkaline-earth-like atoms in optical lattices that can be effectively described by the two-band spin-$1/2$ Hubbard model including the Hund's exchange coupling term. Our main goal is to investigate the effect of exchange interactions on finite-temperature magnetic phases for a wide range of lattice fillings. We use the dynamical mean-field theory approach and its real-space generalization to obtain finite-temperature phase diagrams including transitions to magnetically-ordered phases. It allows to determine optimal experimental regimes for approaching long-range ferromagnetic ordering in ultracold gases. We also calculate the entropy in the vicinity of magnetically-ordered phases, which provides quantitative predictions for on-going and future experiments aiming at approaching and studying long-range ordered states in optical lattices.