Phase separation at all interaction strengths in the t-J model

TL;DR

This study uses advanced Monte Carlo methods to analyze the two-dimensional t-J model, revealing that it exhibits phase separation across all interaction strengths, challenging previous assumptions about its stability at certain dopings.

Contribution

The paper introduces a Green's Function Monte Carlo approach to accurately determine the phase diagram of the t-J model, showing universal phase separation.

Findings

The t-J model phase separates for all J/t values.

It is unstable at dopings previously associated with cuprate superconductivity.

The method provides exact ground-state energies on large lattices.

Abstract

We investigate the phase diagram of the two-dimensional t-J model using a recently developed Green's Function Monte Carlo method for lattice fermions. We use the technique to calculate exact ground-state energies of the model on large lattices. In contrast to many previous studies, we find the model phase separates for all values of J/t. In particular, it is unstable at the hole dopings and interaction strengths at which the model was thought to describe the cuprate superconductors.