Surface and electronic structure of SmB through scanning tunneling microscopy

Abstract

SmB, a so-called Kondo insulator, is recently discussed as a candidate material for a strong topological insulator. We present detailed atomically resolved topographic information on the (0 0 1) surface from more than a dozen SmB samples. Atomically flat, in situ cleaved surfaces often exhibit B- and Sm-terminated surfaces as well as reconstructed and non-reconstructed areas coexisting on different length scales. The terminations are unambiguously identified. In addition, electronic inhomogeneities are observed which likely result from the polar nature of the (0 0 1) surface and may indicate an inhomogeneous Sm valence at the surface of SmB. In addition, atomically resolved topographies on a (1 1 0) surface are discussed.

Keywords:

• Strongly correlated electrons
• Kondo effect
• topological insulator
• scanning tunneling microscopy/spectroscopy

Acknowledgements

The authors gratefully acknowledge experimental help by Tae-Hwan Jang and insightful discussions with Yuri Grin.

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

Work at UC Irvine was supported by the Defense Advanced Research Agency (DARPA) [agreement number FA8650-13-1-7374].