The Phase Diagram of Correlated Electrons in a Lattice of Berry Molecules

TL;DR

This paper investigates a lattice model of correlated electrons with spin-1 degrees of freedom, revealing bound states and phase behavior indicative of Bose gas-like properties with long-range order in 1D and 2D.

Contribution

It introduces a new model incorporating spin-1 degrees of freedom and constrained hopping, analyzing its phase diagram in low density and quarter filling regimes.

Findings

Bound states form even with repulsive interactions in 1D and 2D.

The system exhibits Bose gas-like behavior with off-diagonal long-range order in 2D.

Quantitative phase diagrams are determined for the model.

Abstract

A model for correlated electrons in a lattice with local additional spin--1 degrees of freedom inducing constrained hopping, is studied both in the low density limit and at quarter filling. We show that in both 1D and 2D two particles form a bound state even in presence of a repulsive U<U_c. A picture of a dilute Bose gas, leading to off-diagonal long range order (LRO) in 2D (quasi-LRO in 1D), is supported by quantitative calculations in 1D which allow for a determination of the phase diagram.