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Topological surface state in the Kondo insulator samarium hexaboride

Nature Materials volume 13, pages 466–470 (2014)Cite this article

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Abstract

Topological invariants of electron wavefunctions in condensed matter reveal many intriguing phenomena1,2. A notable example is provided by topological insulators, which are characterized by an insulating bulk coexisting with a metallic boundary state3,4. Although there has been intense interest in Bi-based topological insulators5,6, their behaviour is complicated by the presence of a considerable residual bulk conductivity7,8,9,10. Theories predict11,12 that the Kondo insulator system SmB6, which is known to undergo a transition from a Kondo lattice metal to a small-gap insulator state with decreasing temperature, could be a topological insulator. Although the insulating bulk and metallic surface separation has been demonstrated in recent transport measurements13,14,15, these have not demonstrated the topologically protected nature of the metallic surface state. Here we report thickness-dependent transport measurements on doped SmB6, and show that magnetic and non-magnetic doping results in contrasting behaviour that supports the conclusion that SmB6 shows virtually no residual bulk conductivity.

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Figure 1: Failure of Ohm’s law.
Figure 2: Topological surface state protected by TRS.
Figure 3: Behaviour of magnetic impurities in SmB6.
Figure 4: Quantum percolation of high concentration Yb doped SmB6.

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Acknowledgements

We thank M. Dzero, I. Krivorotov and S. Thomas for discussions. This research was supported by NSF-DMR-0801253, UC Irvine CORCL grant MIIG-2011-12-8 and Sloan Research Fellowship BR2013-116, J.X.

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  1. Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697, USA

    D. J. Kim, J. Xia & Z. Fisk

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  1. D. J. Kim
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Contributions

All authors conceived the idea of the experiment together, D.J.K. and Z.F. grew crystals and D.J.K. made the measurements. All authors discussed the results, participated in data analysis and wrote the manuscript.

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Correspondence to D. J. Kim.

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The authors declare no competing financial interests.

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Kim, D., Xia, J. & Fisk, Z. Topological surface state in the Kondo insulator samarium hexaboride. Nature Mater 13, 466–470 (2014). https://doi.org/10.1038/nmat3913

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