Thermal Conductivity and Magnetic Phase Diagram of CuB2O4

TL;DR

This study investigates how thermal conductivity in CuB2O4 varies with temperature and magnetic field, revealing its sensitivity to magnetic phase boundaries and emphasizing its usefulness in detecting magnetic phase transitions.

Contribution

The paper provides the first detailed analysis of thermal conductivity anisotropy and its relation to magnetic phase boundaries in CuB2O4, highlighting phonon-spin scattering effects.

Findings

Thermal conductivity is nearly isotropic and large in zero field.

Thermal conductivity changes markedly at magnetic phase boundaries.

Phonon-spin scattering influences thermal conductivity near phase transitions.

Abstract

We have measured temperature and magnetic field dependences of the thermal conductivity along the c-axis, kc, and that along the [110] direction, k110, of CuB2O4 single crystals in zero field and magnetic fields along the c-axis and along the [110] direction. It has been found that the thermal conductivity is nearly isotropic and very large in zero field and that the thermal conductivity due to phonons is dominant in CuB2O4. The temperature and field dependences of kc and k110 have markedly changed at phase boundaries in the magnetic phase diagram, which has been understood to be due to the change of the mean free path of phonons caused by the change of the phonon-spin scattering rate at the phase boundaries. It has been concluded that thermal conductivity measurements are very effective for detecting magnetic phase boundaries.