Thermomagnetic Power and Figure of Merit for Spin-1/2 Heisenberg Chain

TL;DR

This study numerically investigates the thermomagnetic properties of the spin-1/2 Heisenberg chain, revealing how magnetic fields influence transport phenomena and the efficiency of thermomagnetic devices.

Contribution

It introduces a numerical evaluation of the magnetic Seebeck coefficient and figure of merit for the Heisenberg chain, highlighting the effects of strong correlations and magnetic fields.

Findings

Magnetic Seebeck coefficient changes sign at certain temperatures.

Strong correlations influence thermomagnetic transport.

Computed figure of merit indicates potential for thermomagnetic device efficiency.

Abstract

Transport properties in the presence of magnetic fields are numerically studied for the spin-1/2 Heisenberg XXZ chain. The breakdown of the spin-reversal symmetry due to the magnetic field induces the magnetothermal effect. In analogy with the thermoelectric effect in electron systems, the thermomagnetic power (magnetic Seebeck coefficient) is provided, and is numerically evaluated by the exact diagonalization for wide ranges of temperatures and various magnetic fields. For the antiferromagnetic regime, we find the magnetic Seebeck coefficient changes sign at certain temperatures, which is interpreted as an effect of strong correlations. We also compute the thermomagnetic figure of merit determining the efficiency of the thermomagnetic devices for cooling or power generation.