Boundary scattering in micro-size crystal of topological Kondo insulator SmB$_6$

TL;DR

This study investigates how boundary scattering affects thermal transport in micro-sized SmB$_6$, revealing boundary scattering's dominant role and complex phonon interactions that influence thermal conductivity at low temperatures.

Contribution

The paper demonstrates that phonon-boundary scattering significantly reduces thermal conductivity in micro-sized SmB$_6$ and uncovers complex phonon interactions affecting thermal transport.

Findings

Thermal conductivity in micro-sized SmB$_6$ is much lower than in bulk.

Boundary scattering dominates thermal resistance at low temperatures.

A double peak in thermal conductivity suggests complex phonon interactions.

Abstract

We have studied the effects of phonon-boundary scattering on the thermal transport in topological Kondo insulator, SmB$_6$. The studies have been performed by using the $3\omega$ method in the temperature range 300K - 3K. We show that the observed thermal conductivity of micro-size SmB$_6$ is of the order of magnitude smaller than for a bulk single-crystal. Using the Callaway model we analyzed the low-temperature lattice thermal conductivity of the micro crystal and show that phonon scattering by sample boundaries plays a major role in the thermal resistance in this topological material. In addition, we show that the temperature dependence of the lattice thermal conductivity shows a double peak structure that suggests complex phonon-phonon or phonon-defects interactions in SmB$_6$. These findings provide guidance for the understanding of the thermal transport of advanced materials and devices at a micro-scale.