Enhancement of the Residual Linear Term in the Thermal Conductivity of Kondo Insulator SmB6 under Uniaxial Tensile Strain

TL;DR

This study investigates how uniaxial tensile strain affects the residual linear term in the thermal conductivity of SmB6, revealing strain-dependent bulk excitations possibly related to Fermionic states without charge.

Contribution

It introduces a novel symmetric measurement geometry and demonstrates strain-dependent enhancement of the residual linear thermal conductivity in SmB6.

Findings

Residual linear thermal conductivity increases with tensile strain.

Strain influences Sm valence, affecting bulk excitations.

Magnetic-field-independent residual terms observed at zero strain.

Abstract

Recent experiments on Kondo insulator SmB6 have revealed bulk excitations that could be Fermions without charge. This would lead to a residual linear term in the thermal conductivity that was not observed universally in experiments. To solve this mystery, we introduce a novel symmetric geometry for performing thermal transport measurements under strains. Magnetic-field-independent residual linear terms were found in flux-grown SmB6 at nominal zero strain, and they grew under a tensile strain, which is known to modify Sm valence. A small growth-dependent difference in the Sm valence might explain the observed discrepancies. We discuss the constraints on the theories of bulk excitations in SmB6.