We have investigated the properties of cleaved SmB6 single crystals by x-ray photoelectron spectroscopy. At low temperatures and freshly cleaved samples a surface core level shift is observed which vanishes when the temperature is increased. A Sm valence between 2.5 - 2.6 is derived from the relative intensities of the Sm2+ and Sm3+ multiplets. The B/Sm intensity ratio obtained from the core levels is always larger than the stoichiometric value. Possible reasons for this deviation are discussed. The B 1s signal shows an unexpected complexity: an anomalous low energy component appears with increasing temperature and is assigned to the formation of a suboxide at the surface. While several interesting intrinsic and extrinsic properties of the SmB6 surface are elucidated in this manuscript no clear indication of a trivial mechanism for the prominent surface conductivity is found.
@article{arxiv.1503.02813,
title = {Surface properties of SmB6 from x-ray photoelectron spectroscopy},
author = {N. Heming and U. Treske and M. Knupfer and B. Büchner and D. S. Inosov and N. Y. Shitsevalova and V. B. Filipov and S. Krause and A. Koitzsch},
journal= {arXiv preprint arXiv:1503.02813},
year = {2015}
}