The measurement of anisotropic thermal transport using time-resolved magneto-optical Kerr effect

Owing to the increasing demand for the improved management of thermal transport in devices, it is necessary to develop an optimal method for the measurement of anisotropic heat conduction. Although several techniques have been used to measure the heat transport in anisotropic materials, the accurate determination of anisotropic thermal conductivity remains a major challenge. In this study, we present time-resolved magneto-optical Kerr effect measurement using a pump-probe technique to investigate the thermal characterization of various materials. A substrate/ferromagnetic metal (FM) structure is prepared, where FM acts as a transducer to detect the thermal transport in substrates of silicon, sapphire, and highly ordered pyrolytic graphite. By performing experiments under various modulation frequencies and laser spot sizes, we determine both in-plane and through-plane thermal conductivities. We also discuss the limitations of measurement and provide useful guidelines to determine the thermal properties of different materials with high accuracy.