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arXiv · 1403.1462

Correlation between bulk thermodynamic measurements and the low temperature resistance plateau in SmB6

W. A. Phelan·S. M. Koohpayeh·P. Cottingham·J. W. Freeland·J. C. Leiner·C. L. Broholm·T. M. McQueen
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Abstract

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.

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W. A. Phelan, S. M. Koohpayeh, P. Cottingham, J. W. Freeland, J. C. Leiner, C. L. Broholm, T. M. McQueen. 2014-06-19. Correlation between bulk thermodynamic measurements and the low temperature resistance plateau in SmB6. https://doi.org/10.1103/physrevx.4.031012

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