Breaking of SU(4) symmetry and interplay between strongly correlated phases in the Hubbard model

TL;DR

This paper investigates the thermodynamic phases of four-component fermionic mixtures in the Hubbard model, focusing on SU(4) symmetry breaking and the effects of symmetry reduction on correlated phases, with implications for ultracold atom experiments.

Contribution

It provides a detailed analysis of phase coexistence and evolution in the Hubbard model as symmetry is lowered from SU(4) to two-band systems, using dynamical mean-field theory.

Findings

Identification of equilibrium phases at half filling

Analysis of entropy to optimize experimental regimes

Evolution of phases with symmetry breaking

Abstract

We study the thermodynamic properties of four-component fermionic mixtures described by the Hubbard model using the dynamical mean-field-theory approach. Special attention is given to the system with SU(4)-symmetric interactions at half filling, where we analyze equilibrium many-body phases and their coexistence regions at nonzero temperature for the case of simple cubic lattice geometry. We also determine the evolution of observables in low-temperature phases while lowering the symmetry of the Hamiltonian towards the two-band Hubbard model. This is achieved by varying interflavor interactions or by introducing the spin-flip term (Hund's coupling). By calculating the entropy for different symmetries of the model, we determine the optimal regimes for approaching the studied phases in experiments with ultracold alkali and alkaline-earth-like atoms in optical lattices.