Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 112: Electronic structure: Surface magnetism and spin phenomena II

O 112.6: Vortrag

Freitag, 16. März 2018, 11:45–12:00, MA 042

Impurity bands and magnetic interactions in the quantum anomalous Hall insulators (V,Cr):(Bi,Sb)₂Te₃ — •Thiago R. F. Peixoto¹, Sonja Schatz¹, Can Raphael Crespo-Vidal¹, Hendrik Bentmann¹, Kai Fauth¹, Martin Winnerlein¹, Steffen Schreyeck¹, Charles Gould¹, Karl Brunner¹, Arthur Ernst^2,3, Laurens W. Molenkamp¹, and Friedrich Reinert¹ — ¹Exp. Phys. VII, II and III, Universität Würzburg — ²Max Planck Institute of Microstructure Physics, Halle (Saale) — ³Institute for Theoretical Physics, Johannes Kepler Universität Linz, Austria

Recently we have reported on the fingerprint of the 3d impurity states in the valence band of the quantum anomalous Hall system V:(BiSb)₂Te₃ by means of resonant photoemission spectroscopy (resPES) [1]. These states lie at the Fermi level and carry a significant magnetic moment, so that they are expected to promote a ferromagnetic superexchange interaction between the magnetic dopants via pd hybridization. Here we report x-ray magnetic circular dichroism (XMCD) measurements at the L_2,3 edges of both V- and Cr-doped (BiSb)₂Te₃ thin films. We show the ferromagnetic character of V and Cr 3d impurity bands at temperatures below 50 K. We compare our XMCD data with our valence band resPES results, which are supported by ab initio calculations of the density of states (DOS), and discuss the implications of V and Cr 3d-DOS to the magnetism of magnetically doped topological insulators.

[1] T. R. F. Peixoto et al., Physical Review B 94, 195140 (2016).