Topological insulators are materials characterized by dissipationless, spin-polarized surface states resulting from non-trivial band topologies. Recent theoretical models and experiments suggest that SmB6 is the first topological Kondo insulator, in which the topologically non-trivial band structure results from electron-electron interactions via Kondo hybridization. Here, we report that the surface conductivity of SmB6 increases systematically with bulk carbon content. Further, addition of carbon is linked to an increase in n-type carriers, larger low temperature electronic contributions to the specific heat with a characteristic temperature scale of T* = 17 K, and a broadening of the crossover to the insulating state. Additionally, X-ray absorption spectroscopy shows a change in Sm valence at the surface. Our results highlight the importance of phonon dynamics in producing a Kondo insulating state and demonstrate a correlation between the bulk thermodynamic state and low temperature resistance of SmB6.
@article{arxiv.1403.1462,
title = {Correlation between bulk thermodynamic measurements and the low temperature resistance plateau in SmB6},
author = {W. A. Phelan and S. M. Koohpayeh and P. Cottingham and J. W. Freeland and J. C. Leiner and C. L. Broholm and T. M. McQueen},
journal= {arXiv preprint arXiv:1403.1462},
year = {2014}
}