Large magnetic heat transport in a Haldane chain material Ni(C$_3H_{10}N_2)_2NO_2ClO_4

TL;DR

This study investigates heat transport in a Haldane chain compound, revealing significant magnetic contributions and anisotropic thermal conductivity influenced by magnetic fields, especially near the critical field where the spin gap is minimized.

Contribution

It demonstrates large magnetic heat transport in a Haldane chain material and shows how magnetic fields affect anisotropic thermal conductivity through spin spectrum modifications.

Findings

Anisotropic thermal conductivity with magnetic contribution along the spin chain.

Magnetic field causes peak-like increase in conductivity along the chain.

Significant magnetic thermal transport observed near the critical field.

Abstract

We report a study on the heat transport of an S = 1 Haldane chain compound Ni(C_3H_{10}N_2)_2NO_2ClO_4 at low temperatures and in magnetic fields. The zero-field thermal conductivities show a remarkable anisotropy for the heat current along the spin-chain direction (\kappa_b) and the vertical direction (\kappa_c), implying a magnetic contribution to the heat transport along the spin-chain direction. The magnetic-field-induced change of the spin spectrum has obviously opposite impacts on \kappa_b and \kappa_c. In particular, \kappa_b(H) and \kappa_c(H) curves show peak-like increases and dip-like decreases, respectively, at \sim 9 T, which is the critical field that minimizes the spin gap. These results indicate a large magnetic thermal transport in this material.