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