On the phase diagram of the zero-bandwidth extended Hubbard model with intersite magnetic interactions for strong on-site repulsion limit

TL;DR

This paper investigates the phase diagram of a zero-bandwidth extended Hubbard model with intersite magnetic interactions, using Monte Carlo simulations and variational methods to identify various magnetic and phase-separated states.

Contribution

It provides the first detailed phase diagrams of this model on a 2D square lattice, comparing Monte Carlo and variational approaches for the first time.

Findings

Identification of homogeneous magnetic phases and phase separation.

Comparison of Monte Carlo and variational results.

Dependence of phases on interaction parameters and electron concentration.

Abstract

In this report we have analyzed a simple effective model for a description of magnetically ordered insulators. The Hamiltonian considered consists of the effective on-site interaction (U) and the intersite Ising-like magnetic exchange interaction (J) between nearest neighbors. For the first time the phase diagrams of this model have been determined within Monte Carlo simulation on 2D-square lattice. They have been compared with results obtained within variational approach, which treats the on-site term exactly and the intersite interactions within mean-field approximation. We show within both approaches that, depending on the values of interaction parameters and the electron concentration, the system can exhibit not only homogeneous phases: (anti-)ferromagnetic (F) and nonordered (NO), but also phase separated states (PS: F-NO).