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arXiv · 1503.02813

Surface properties of SmB6 from x-ray photoelectron spectroscopy

N. Heming·U. Treske·M. Knupfer·B. Büchner·D. S. Inosov·N. Y. Shitsevalova·V. B. Filipov·S. Krause·A. Koitzsch
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Abstract

We have investigated the properties of cleaved SmB$_6$ 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 Sm$^{2+}$ and Sm$^{3+}$ 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 SmB$_6$ surface are elucidated in this manuscript no clear indication of a trivial mechanism for the prominent surface conductivity is found.

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N. Heming, U. Treske, M. Knupfer, B. Büchner, D. S. Inosov, N. Y. Shitsevalova, V. B. Filipov, S. Krause, A. Koitzsch. 2015-03-10. Surface properties of SmB6 from x-ray photoelectron spectroscopy. https://doi.org/10.1103/physrevb.90.195128

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