Polarity-driven surface metallicity in SmB$_6$

ORAL

Abstract

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 2$p$ dangling bonds, on a polar surface [1]. 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. \\[4pt] [1] Z.-H. Zhu et al., Phys. Rev. Lett. to appear (arXiv:1309.2945)

–

Authors

  • Andrea Damascelli

    • Department of Physics and Astronomy, University of British Columbia; Quantum Matter Institute, University of British Columbia
    • University of British Columbia, Vancouver, Canada

  • Z.-H. Zhu

    • University of British Columbia, Vancouver, Canada

  • A. Nicolaou

    • University of British Columbia, Vancouver, Canada

  • G. Levy

    • University of British Columbia, Vancouver, Canada

  • N.P. Butch

    • University of Maryland, College Park, USA

  • P. Syers

    • University of Maryland, College Park, USA

  • X.F. Wang

    • University of Maryland, College Park, USA

  • J. Paglione

    • University of Maryland, College Park, USA

  • G.A. Sawatzky

    • University of British Columbia, Vancouver, Canada

  • I.S. Elfimov

    • University of British Columbia, Vancouver, Canada