Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 14: Electronic Structure of Surfaces: Magnetism and Spin Phenomena II
O 14.2: Vortrag
Montag, 20. März 2017, 15:15–15:30, WIL C107
Impurity states and ferromagnetic superexchange interactions in the magnetic topological insulator V:(Bi,Sb)2Te3: a combined resonant photoemission and x-ray magnetic circular dichroism study — •Thiago R. F. Peixoto1, Hendrik Bentmann1, Sonja Schatz1, Steffen Schreyeck2, Martin Winnerlein2, Charles Gould2, Karl Brunner2, Kai Fauth3, Arthur Ernst4, Laurens W. Molenkamp2, and Friedrich Reinert1 — 1EP VII, Uni-Würzburg, Germany — 2EP III, Uni-Würzburg, Germany — 3EP II, Uni-Würzburg, Germany — 4Max Planck Institute of Microstrocture Physics, Halle, Germany
Recently we have demonstrated the impurity character of the V 3d density of states (DOS) at V:(Bi,Sb)2Te3 magnetic topological insulator thin films [1], a newly reported quantum anomalous Hall system (QAHS), by resonant photoemission spectroscopy (resPES). Here we used resPES at the Cr L2,3 edges to extract the Cr 3d DOS of Cr:(Bi,Sb)2Te3 thin films, another QAHS, and compare with the V 3d states. In addition, we probed x-ray magnetic circular dichroism (XMCD) of the V 3d states, showing a persistent ferromagnetic character up to 50 K. A small opposite XMCD signal was observed at the Sb M5 edge, evidencing an induced antiparallel magnetic moment at the Sb atom, as recently reported for Cr:(Bi,Sb)2Te3 [2]. The 3d impurity states are expected to mediate a ferromagnetic superexchange interaction, thus contributing to the ferromagnetism in these systems.
[1] T. R. F. Peixoto et al., Phys. Rev. B 94, 195140 (2016).
[2] M. Ye et al., Nat. Commun. 6, 8913 (2015).