Theory Of The One Dimensional SU(4) Spin-Orbital Model

TL;DR

This paper analyzes the one-dimensional SU(4) spin-orbital model using Abelian bosonization, revealing a massless phase with algebraic correlations and a massive phase with dimerization and approximate SO(6) symmetry.

Contribution

It derives the low-energy effective theory for the model, exploring deviations from SU(4) symmetry and characterizing the phases and their symmetries.

Findings

Existence of a massless phase with algebraic correlations

Identification of a massive phase with dimerization and SO(6) symmetry

Description of phase transition behavior

Abstract

The one-dimensional spin-orbital model is studied by means of Abelian bosonization. We derive the low-energy effective theory which enables us to study small deviations from the SU(4) symmetric point. We show that there exists a massless region with algebraically decaying correlation functions, $\sim \cos(\pi/{2a_0} x) x^{-3/2}$. When entering the massive phase, the system displays an approximate SO(6) enlarged symmetry with a dimerization type of ordering consisting in alternating spin and orbital singlets.