Competition between the Spin and Pseudospin Subsystems in a Model Cuprate

TL;DR

This paper investigates the interplay between magnetic and charge orderings in a simplified 2D spin-pseudospin model of cuprates, revealing phase separation phenomena and differences under strong exchange or charge correlations.

Contribution

It introduces a simplified 2D spin-pseudospin model for cuprates and compares mean-field and Monte Carlo results, highlighting phase separation and stability conditions.

Findings

Strong exchange leads to phase separation into immiscible subsystems.

Mean-field and Monte Carlo results show qualitative differences.

Analytical expression derived for phase separation temperature.

Abstract

The competition between the magnetic and charge orderings in a model cuprate is considered in terms of a simplified static 2D spin-pseudospin model. This model is equivalent to the 2D dilute antiferromagnetic (AFM) Ising model with charged impurities. The mean-field approximation results are presented for the system under study and briefly compared to the classical Monte Carlo (MC) calculations. The numerical simulation shows that the cases of the strong exchange and the strong charge correlation differ qualitatively. In the case of a strong exchange, the AMF phase is instable with respect to the phase separation (PS) into the pseudospin (charge) and magnetic (spin) subsystems that behave as immiscible quantum liquids. The analytical expression has been obtained for the PS temperature.