%0 Journal Article
%T Polarity-driven surface metallicity in SmB$_6$
%A Z. -H. Zhu
%A A. Nicolaou
%A G. Levy
%A N. P. Butch
%A P. Syers
%A X. F. Wang
%A J. Paglione
%A G. A. Sawatzky
%A I. S. Elfimov
%A A. Damascelli
%J Physics
%D 2013
%I arXiv
%R 10.1103/PhysRevLett.111.216402
%X By a combined angle-resolved photoemission spectroscopy and density functional theory study, we discover that the surface metallicity is polarity-driven in SmB$_6$. Two surface states, not accounted for by the bulk band structure, are reproduced by slab calculations for coexisting B$_6$ and Sm surface terminations. Our analysis reveals that a metallic surface state stems from an unusual property, generic to the (001) termination of all hexaborides: the presence of boron $2p$ dangling bonds, on a polar surface. The discovery of polarity-driven surface metallicity sheds new light on the 40-year old conundrum of the low-temperature residual conductivity of SmB$_6$, and raises a fundamental question in the field of topological Kondo insulators regarding the interplay between polarity and nontrivial topological properties.
%U http://arxiv.org/abs/1309.2945v2