The ferromagnetic topological insulator V:(Bi,Sb)2Te3 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)2Te3 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.
@article{arxiv.1607.01662,
title = {Impurity states in the magnetic topological insulator V:(Bi,Sb)$_2$Te$_3$},
author = {Thiago R. F. Peixoto and Hendrik Bentmann and Steffen Schreyeck and Martin Winnerlein and Christoph Seibel and Henriette Maaß and Mohammed Al-Baidhani and Katharina Treiber and Sonja Schatz and Stefan Grauer and Charles Gould and Karl Brunner and Arthur Ernst and Laurens W. Molenkamp and Friedrich Reinert},
journal= {arXiv preprint arXiv:1607.01662},
year = {2016}
}
Comments
5 pages, 3 figures, figure 3 changed, new references and discussion included