Magnetic orderings and phase separations in the zero-bandwidth limit of the extended Hubbard model with intersite magnetic interactions

TL;DR

This paper investigates magnetic orderings and phase separation phenomena in a simplified extended Hubbard model with intersite magnetic interactions, revealing diverse phases depending on interaction parameters and electron concentration.

Contribution

It introduces a variational approach to analyze magnetic phases and phase separation in a zero-bandwidth extended Hubbard model with intersite magnetic interactions.

Findings

Identification of ferromagnetic, non-ordered, and phase-separated states.

Dependence of phase stability on interaction parameters and electron concentration.

Phase diagrams illustrating various magnetic and phase-separated regimes.

Abstract

A simple effective model for a description of magnetically ordered insulators is analysed. The tight binding Hamiltonian consists of the effective on-site interaction (U) and intersite magnetic exchange interactions (Jz, Jxy) between nearest-neighbours. The phase diagrams of this model have been determined within the variational approach, which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation. We show 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).