Dresden 2011 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 40: Topological Insulators (jointly with HL, MA)
TT 40.8: Vortrag
Mittwoch, 16. März 2011, 18:30–18:45, HSZ 04
Tolerance of topological surface state towards adsorbed magnetic moments: Fe on Bi2Te3 — •Markus Scholz1, Dmitry Marchenko1, Jaime Sanchez-Barriga1, Andrei Varykhalov1, Andrei Volykhov2, Lada Yashina2, and Oliver Rader1 — 1Helmholtz-Zentrum für Materialien und Energie, Berlin, Deutschland — 2Moscow State University, Moskau, Russland
Topological surface states on Bi2Se3 and Bi2Te3 are protected by time reversal symmetry [1]. Magnetic fields break time-reversal symmetry, and they have been used in two-dimensional spin quantum-Hall systems to destroy the topological edge states [2]. Another possibility is to introduce magnetic moments. This has been done by substitution of Mn and Fe into the bulk [3][4]. For Fe a small gap of 44meV was created, however, at very large amounts (12%). In this work, we deposit Fe directly onto the surface where the topological surface state is localized. We show for coverages of 0.25 and 1 ML Fe that the Dirac point remains intact and no gap appears. Core level spectroscopy of Bi and Te states gives insight into the interaction between substrate and adatoms. In addition, extra surface states appear at the Fermi energy which show a large Rashba-type spin-orbit splitting. The orientation of the spin of both, the topological as well as the Rashba-type split surface states is analysed. [1] Kane and Mele, Phy. Rev. Lett 95, 146802 (2005); Liang Fu et al., Phys. Rev. Lett. 98, 106803 (2007) [2] König et al.,Science 318, 5851 (2007) [3] Hsieh et al., Phys. Rev. Lett. 103, 146401 (2009) [4] Chen et al., Science 329, 5992 (2010)