Large magnetothermal conductivity of HoMnO_3 single crystals and its relation to the magnetic-field induced transitions of magnetic structure

TL;DR

This study investigates the low-temperature heat transport in HoMnO_3 single crystals, revealing strong magnetic-field dependence and complex magnetic transitions, highlighting significant spin-phonon coupling in this multiferroic material.

Contribution

It provides new insights into the magnetic-field-induced transitions of magnetic structures and their impact on thermal conductivity in HoMnO_3.

Findings

Thermal conductivity shows up to 90% suppression under magnetic field.

Thermal conductivity increases up to 20 times at certain fields.

Complex magnetic phase diagram with field-induced spin re-orientations.

Abstract

We study the low-temperature heat transport of HoMnO_3 single crystals to probe the magnetic structures and their transitions induced by magnetic field. It is found that the low-T thermal conductivity (\kappa) shows very strong magnetic-field dependence, with the strongest suppression of nearly 90% and the biggest increase of 20 times of \kappa compared to its zero-field value. In particular, some ``dip"-like features show up in \kappa(H) isotherms for field along both the ab plane and the c axis. These behaviors are found to shed new light on the complex H-T phase diagram and the field-induced re-orientations of Mn^{3+} and Ho^{3+} spin structures. The results also demonstrate a significant spin-phonon coupling in this multiferroic compound.