Low-Temperature Thermodynamics of $A^{(2)}_2$ and su(3)-invariant Spin Chains

TL;DR

This paper derives and solves thermodynamic Bethe Ansatz equations for the $A^{(2)}_2$ quantum spin chain, revealing its low-temperature thermodynamic properties and connecting it to the su(3)-invariant chain.

Contribution

It formulates the TBA equations for the $A^{(2)}_2$ chain in a magnetic field and demonstrates their reduction to su(3) results as anisotropy vanishes.

Findings

Calculated specific heat and magnetic susceptibility at low temperature and small field.

Established connection between $A^{(2)}_2$ and su(3)-invariant chains in the anisotropy limit.

Abstract

We formulate the thermodynamic Bethe Ansatz (TBA) equations for the closed (periodic boundary conditions) $A^{(2)}_2$ quantum spin chain in an external magnetic field, in the (noncritical) regime where the anisotropy parameter $\eta$ is real. In the limit $\eta \to 0$, we recover the TBA equations of the antiferromagnetic su(3)-invariant chain in the fundamental representation. We solve these equations for low temperature and small field, and calculate the specific heat and magnetic susceptibility.