Optical Thermal Diffusivity Measurements in RETe₃

RETe3 are a family of quasi-2D metal with one or two stripe ordered charge density wave (CDW) orders and can have Pd intercalated between the layers [1]. We use a photo-thermal microscope for high resolution thermal diffusivity and optical differential reflectivity measurements in PdxErTe3 and TbTe3 by measuring phase delay in local reflectivity. This is supplemented with specific heat and direct thermal conductivity measurements. Our main observation is below the primary CDW transition temperature, there is observed a strong anomaly in the diffusivity while the conductivity and specific heat change less and more broadly. We will further discuss the relation between thermal and charge transport, and the applicability of Einstein relation kappa=cD and the Wiedemann-Franz law near the CDW transitions.

[1] E. D. Kountz, et al., Phys. Rev. B 104, L241109 (2021).