Frequency-Domain Magneto-Optical Kerr Effect for thermal property measurements of anisotropic 2-dimensional materials

The rapidly increasing number of 2-dimensional materials that have been isolated or synthesized provides an enormous opportunity to realize new device functionalities. Whereas optical and electrical characterization has been more readily applicable to these new materials, quantitative thermal characterization is more challenging due to the difficulties with localizing heat flow. Optical pump-probe techniques that are well-established for the study of bulk materials or thin-films have limited sensitivity to lateral heat transport, and the characterization of the thermal anisotropy that is common in 2-dimensional materials is therefore challenging. Here we present a new method to quantify the thermal properties based on the magneto-optical Kerr effect that yields enhanced sensitivity to in-plane heat transport. Using a magnetic material as transducer for heat transport allows the use of semi-transparent layers that are very thin, increasing the in-plane thermal gradients. We apply this approach to measure the thermal properties of a range of 2-dimensional materials which are of interest for device applications, including single layer graphene and h-BN, multilayer h-BN and MoS₂, and bulk MoSe₂.