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arXiv · 1607.01662

Impurity states in the magnetic topological insulator V:(Bi,Sb)$_2$Te$_3$

Thiago R. F. Peixoto·Hendrik Bentmann·Steffen Schreyeck·Martin Winnerlein·Christoph Seibel·Henriette Maaß·Mohammed Al-Baidhani·Katharina Treiber·Sonja Schatz·Stefan Grauer·Charles Gould·Karl Brunner·Arthur Ernst·Laurens W. Molenkamp·Friedrich Reinert
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Abstract

The ferromagnetic topological insulator V:(Bi,Sb)$_2$Te$_3$ has been recently reported as a quantum anomalous Hall (QAH) system. Yet the microscopic origins of the QAH effect and the ferromagnetism remain unclear. One key aspect is the contribution of the V atoms to the electronic structure. Here the valence band of V:(Bi,Sb)$_2$Te$_3$ thin films was probed in an element-specific way by resonant photoemission spectroscopy. The signature of the V $3d$ impurity band was extracted, and exhibits a high density of states near Fermi level. First-principles calculations support the experimental results and indicate the coexistence of ferromagnetic superexchange and double exchange interactions. The observed impurity band is thus expected to contribute to the ferromagnetism via the interplay of different mechanisms.

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Thiago R. F. Peixoto, Hendrik Bentmann, Steffen Schreyeck, Martin Winnerlein, Christoph Seibel, Henriette Maaß, Mohammed Al-Baidhani, Katharina Treiber, Sonja Schatz, Stefan Grauer, Charles Gould, Karl Brunner, Arthur Ernst, Laurens W. Molenkamp, Friedrich Reinert. 2016-07-06. Impurity states in the magnetic topological insulator V:(Bi,Sb)$_2$Te$_3$. https://doi.org/10.1103/physrevb.94.195140

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