Chemical and valence reconstruction at the surface of SmB6 revealed by means of resonant soft x-ray reflectometry

作     者：V. B. Zabolotnyy K. Fürsich R. J. Green P. Lutz K. Treiber Chul-Hee Min A. V. Dukhnenko N. Y. Shitsevalova V. B. Filipov B. Y. Kang B. K. Cho R. Sutarto Feizhou He F. Reinert D. S. Inosov V. Hinkov 

作者机构：Experimentelle Physik IV and Röntgen Center for Complex Materials Systems (RCCM) Universität Würzburg Am Hubland 97074 Würzburg Germany Stewart Blusson Quantum Matter Institute Department of Physics & Astronomy University of British Columbia 2355 East Mall Vancouver Canada V6T 1Z4 Department of Physics & Engineering Physics University of Saskatchewan Saskatoon Saskatchewan Canada S7N 5E2 Experimentelle Physik VII and Röntgen Center for Complex Materials Systems (RCCM) Universität Würzburg Am Hubland 97074 Würzburg Germany I. M. Frantsevich Institute for Problems of Materials Science of NAS 3 Krzhyzhanovsky Street Kiev 03680 Ukraine School of Materials Science and Engineering Gwangju Institute of Science and Technology Gwangju 500-712 Korea Canadian Light Source Inc. Saskatoon Saskatchewan Canada S7N 2V3 Institut für Festkörper- und Materialphysik TU Dresden D-01069 Dresden Germany 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2018年第97卷第20期

页      面：205416-205416页

核心收录：

基　　金：Western Economic Diversification Canada, WD National Research Foundation of Korea, NRF Government of Saskatchewan University of Saskatchewan, UOS Bank for Quantum Electronic Materials-BQEM000652 Canada Foundation for Innovation, CFI Max Planck-UBC Centre for Quantum Materials Natural Sciences and Engineering Research Council of Canada, NSERC National Research Council Canada, NRC Deutsche Forschungsgemeinschaft, DFG, (C06, IN 209/3-2, SFB 1170, SFB 1143) Ministry of Education, MOE, (NRF-2017R1A2B2008538) Office of Science, SC, (DE-AC02-05CH11231) 

主　　题：Electronic structure Surface reconstruction Surface states Topological materials Crystal-field theory Density functional calculations Photoelectron emission microscopy X-ray absorption spectroscopy X-ray reflectivity X-ray techniques 

摘      要：Samarium hexaboride (SmB6), a Kondo insulator with mixed valence, has recently attracted much attention as a possible host for correlated topological surface states. Here, we use a combination of x-ray absorption and reflectometry techniques, backed up with a theoretical model for the resonant M4,5 absorption edge of Sm and photoemission data, to establish laterally averaged chemical and valence depth profiles at the surface of SmB6. We show that upon cleaving, the highly polar (001) surface of SmB6 undergoes substantial chemical and valence reconstruction, resulting in boron termination and a Sm3+ dominated subsurface region. Whereas at room temperature, the reconstruction occurs on a timescale of less than 2 h, it takes about 24 h below 50 K. The boron termination is eventually established, irrespective of the initial termination. Our findings reconcile earlier depth resolved photoemission and scanning tunneling spectroscopy studies performed at different temperatures and are important for better control of surface states in this system.