Loop Current and Antiferromagnetic States in Fermionic Hubbard Model with Staggered Flux at Half Filling

TL;DR

This paper investigates phase transitions and loop currents in a strongly correlated fermionic Hubbard model with staggered flux, revealing an insulating coexistent state with loop currents at half filling.

Contribution

It introduces a variational Monte Carlo study of a fermionic Hubbard model with staggered flux, highlighting the emergence of an insulating state with loop currents and coexistence of magnetic and flux orders.

Findings

Ground state is an insulating coexistent state with loop currents.

Strong correlations lead to a phase with antiferromagnetic and flux order coexistence.

Comparison with bosons emphasizes the Pauli principle's role.

Abstract

Anticipating realization of interacting fermions in an optical lattice with a large gauge field, we consider phase transitions and loop currents in a two-dimensional S=1/2 fermionic-Hubbard model with $\pi$/2-staggered flux at half filling. We use a variational Monte Carlo method, which is reliable even for strong correlations. As a trial wave function, a coexistent state of antifferomagnetic and staggered-flux orders is studied. In a strongly correlated regime, the ground state becomes an insulating coexistent state with loop currents. By comparing fermions with bosons, we discuss an important role of Pauli principle.