Berlin 2015 – wissenschaftliches Programm
TT 71.1: Poster
Mittwoch, 18. März 2015, 15:00–18:00, Poster B
Surface properties of SmB6 from x-ray photoemission spectroscopy — •Nadine Heming1, Uwe Treske1, Martin Knupfer1, Bernd Büchner1,2, Dmytro Inosov2, Natalya Y. Shitsevalova3, Volodymyr B. Filipov3, Stephan Kraus4, and Andreas Koitzsch1 — 1Institute for Solid State Research, IFW Dresden — 2Institut für Festkörperphysik, TU Dresden — 3Institute for Problems of Material Sciences, Kiev — 4BESSY II, Berlin
The mixed valence compound SmB6 has been well known for its anomalous low temperature resistivity behavior for decades: At temperatures below 50 K, SmB6 transmutes from a metal to an insulator but shows residual resistivity for temperatures less than 5K. Renewed interest in this material comes from theoretical proposals, predicting topological protected surface states making this compound the prime candidate for the new material class of ’"Topological Kondo Insulators’". Indeed, elaborate transport experiments have evidenced that the residual conductivity occurs only at the surface. However, it is generally well known that the surface of f-systems undergoes valence changes and reconstructions, which may also influence the surface properties of this material. Applying surface sensitive soft x-ray photoemission spectroscopy, we have investigated the surface properties of freshly cleaved SmB6 single crystals at 15K monitoring the Sm valance, the chemical state of boron as well as the surface stoichiometry, and also the development of these over time and with increased temperature: We have found that the surface shows an unexpected complexity stemming from both intrinsic and extrinsic changes.