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O: Fachverband Oberflächenphysik

O 66: Electronic Structure of Surfaces

O 66.1: Poster

Mittwoch, 18. März 2015, 18:15–21:00, Poster A

XMCD of 3d adatoms on Bi₂Te₃ and Bi₂Te₂Se: experiment and ab initio theory — Martin Vondracek¹, •Jan Honolka¹, Cinthia Piamonteze², Jonas Warmuth⁴, Matteo Michiardi³, Philip Hofmann³, Khajetoorians Alexander Ako⁴, Jens Wiebe⁴, Roland Wiesendanger⁴, Tim Wehling⁵, Jan Minar⁶, Hubert Ebert⁶, Jian-Li Mi³, Bo B. Iversen³, and Markus Dunst⁶ — ¹Inst. of Physics ASCR, Prague, Czech Republic — ²PSI, Switzerland — ³iNano, Aarhus University, Denmark — ⁴INF, University of Hamburg, Germany — ⁵Inst. of Theo. Physics, University of Bremen, Germany — ⁶LMU München, Germany

The chalcogenide 3D topological insulator Bi₂Te₃ obeys time-reversal symmetry, and hosts a linear dispersive, topological surface state around the Gamma point[1]. It is predicted, that magnetic adatoms can break time-reversal symmetry, thereby generating an energy gap at the Dirac point of the otherwise topologically protected surface states[2]. Here we summarize experimental XAS and XMCD results of single 3d adatoms Ni, Fe, and Cu on Bi₂Te₃ and Bi₂Te₂Se surfaces. While Cu shows a d¹⁰ electronic configuration, we find a significant resonant Ni L_2,3 intensity in XAS, however no magnetic dichroism within the detection limit. The results are compared to ab initio theory. Calculated equilibrium positions of adatoms and their host structure show strong relaxation effects. d-shell occupancies and magnetic properties are extracted. Moreover, we present simulated resonant spectral shapes. [1] M. Z. Hasan and C. L. Kane, Reviews of Modern Physics 82, 3045 (2010). [2] Y. L. Chen et al., Science 329, 659 (2010).