Thermodynamics of a one-dimensional S=1/2 spin-orbital model

TL;DR

This paper investigates the thermodynamic behavior of a one-dimensional spin-orbital model with SU(4) symmetry, revealing temperature-dependent correlation lengths and a tendency towards dimerization.

Contribution

It provides a detailed numerical analysis of the thermodynamics of a spin-orbital model, highlighting the role of SU(4) symmetry and the evolution of correlation lengths with temperature.

Findings

Presence of an integrable SU(4)-symmetric point.

Correlation lengths evolve intriguingly with temperature.

Model shows a tendency towards dimerization at finite temperature.

Abstract

The thermodynamic properties of a one-dimensional model describing spin dynamics in the presence of a twofold orbital degeneracy are studied numerically using the transfer-matrix renormalization group (TMRG). The model contains an integrable SU(4)-symmetric point and a gapless phase which is SU(4) invariant up to a rescaling of the velocities for spin and orbital degrees of freedom which allows detailed comparison of the numerical results with conformal field theory. We pay special attention to the correlation lengths which show an intriguing evolution with temperature. We find that the model shows an intrinsic tendency towards dimerization at finite temperature even if the ground state is not dimerized.