The thermal conductivity of alternating spin chains

TL;DR

This paper investigates the thermal conductivity of integrable alternating spin chains, deriving integral equations for thermal transport and analyzing their behavior at low temperatures, revealing universal properties linked to the model's integrability.

Contribution

It introduces a novel approach to compute thermal conductivity in alternating spin chains using conserved currents and integral equations, extending understanding of thermal transport in integrable quantum systems.

Findings

Thermal Drude weight is proportional to temperature at low T.

Derived non-linear integral equations for thermal conductivity.

Numerical solutions for specific spin configurations.

Abstract

We study a class of integrable alternating (S1,S2) quantum spin chains with critical ground state properties. Our main result is the description of the thermal Drude weight of the one-dimensional alternating spin chain as a function of temperature. We have identified the thermal current of the model with alternating spins as one of the conserved currents underlying the integrability. This allows for the derivation of a finite set of non-linear integral equations for the thermal conductivity. Numerical solutions to the integral equations are presented for specific cases of the spins S1 and S2. In the low-temperature limit a universal picture evolves where the thermal Drude weight is proportional to temperature T and central charge c.