Boundary scattering in topological Kondo insulator SmB₆

We have studied the effects of phonon-boundary scattering on the thermal transport of topological Kondo insulator SmB₆. The studies have been performed using the 3 ω method across a temperature range 3-300 K. Our results indicate that the thermal conductivity of micro-sized SmB₆ is of an order of magnitude smaller than that of a bulk single crystal. Using the Callaway model, we analyzed the low-temperature lattice thermal conductivity of the microcrystal and demonstrated that phonon scattering at the sample boundaries is a major contributor to the thermal resistance in this topological material. Furthermore, our study reveals that the temperature dependence of the lattice thermal conductivity exhibits a double-peak structure, suggesting strong phonon-phonon or phonon-defect interactions in this material, characteristic of resonant scattering. These findings will help in a better understanding of thermal transport in advanced materials and devices at the micro scale.