Hubbard-Shastry lattice models

TL;DR

This paper analyzes two exactly-solvable one-dimensional lattice models for strongly correlated electrons, exploring their phase diagrams, thermodynamic properties, and extensions, revealing diverse magnetic and insulating behaviors.

Contribution

It introduces two new models derived from Shastry's R-matrix, expanding the class of exactly-solvable strongly correlated electron systems.

Findings

One model shows itinerant ferromagnetism.

The other forms bound pairs and becomes insulating at half-filling.

Derived TBA equations and phase diagrams at zero temperature.

Abstract

We consider two lattice models for strongly correlated electrons which are exactly-solvable in one dimension. Along with the Hubbard model and the su(2|2) spin chain, these are the only parity-invariant models that can be obtained from Shastry's R-matrix. One exhibits itinerant ferromagnetic behaviour, while for the other the electrons form bound pairs and at half-filling the model becomes insulating. We derive the TBA equations for the models, analyze them at various limits, and in particular obtain zero temperature phase diagrams. Furthermore we consider extensions of the models, which reduce to the Essler-Korepin-Schoutens model in certain limits.