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TT: Fachverband Tiefe Temperaturen

TT 92: Topological Insulators I (jointly with MA, DS, HL, O)

TT 92.7: Vortrag

Donnerstag, 19. März 2015, 11:00–11:15, EB 202

The magnetism of Ni adatoms adsorbed on the TI Bi₂Te₂Se — Jan Honolka¹, Martin Vondráček¹, •Lasse Cornils², Malte Schüler³, Markus Dunst⁴, Jonas Warmuth², Lihui Zhou², Anand Kamlapure², Alexander Ako Khajetoorians^2,5, Matteo Michiardi⁶, Lucas Barreto⁶, Philip Hofmann⁶, Jian-Li Mi⁶, Martin Bremholm⁶, Bo B. Iversen⁶, Cinthia Piamonteze⁷, Hubert Ebert⁴, Jan Minar^4,8, Tim Wehling³, Roland Wiesendanger², and Jens Wiebe² — ¹Inst. of Physics ASCR, Prague, Czech Republic — ²INF, University of Hamburg, Germany — ³Inst. of Theo. Physics, University of Bremen, Germany — ⁴LMU München, Germany — ⁵IMM, Radboud University Nijmegen, The Netherlands — ⁶iNano, Aarhus University, Denmark — ⁷PSI, Switzerland — ⁸New Technologies-Research Center, University of West Bohemia, Pilsen, Czech Republic

The predicted gap opening in the surface state of topological insulators (TIs) induced by surface magnetic doping, and the associated novel electron phases, have recently caught strong interest of the scientific community. However, the experimental evidence of an induced gap opening is still controversial [1] and calls for a detailed investigation of the magnetism of different adatoms. Here, we show by a combined XMCD, ARPES and STS study, that Ni adatoms on the TI Bi₂Te₂Se reveal a surprising behaviour: While there is no detectable XMCD signal at the Ni L_2,3-edges, the XAS spectrum unveils a considerable resonant absorption of the d-shell. The results are analyzed by ab-initio calculations. [1] J. Honolka et al., PRL 108, 256811 (2012).