Journal Article

FZJ-2020-04720

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Non-local effect of impurity states on the exchange coupling mechanism in magnetic topological insulators

Peixoto, T. R. F. (Corresponding author) ; Bentmann, H. ; Rüßmann, P.FZJ* ; Tcakaev, A.-V. ; Winnerlein, M. ; Schreyeck, S. ; Schatz, S. ; Vidal, R. C. ; Stier, F. ; Zabolotnyy, V. ; Green, R. J. ; Min, C. H. ; Fornari, C. I. ; Maaß, H. ; Vasili, H. B. ; Gargiani, P. ; Valvidares, M. ; Barla, A. ; Buck, J. ; Hoesch, M. ; Diekmann, F. ; Rohlf, S. ; Kalläne, M. ; Rossnagel, K. ; Gould, C. ; Brunner, K. ; Blügel, S.FZJ* ; Hinkov, V. ; Molenkamp, L. W. ; Reinert, F.

2020
Nature Publishing Group [London]

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Please use a persistent id in citations: http://hdl.handle.net/2128/26265  doi:10.1038/s41535-020-00288-0

Abstract: Since the discovery of the quantum anomalous Hall (QAH) effect in the magnetically doped topological insulators (MTI) Cr:(Bi,Sb)2Te3 and V:(Bi,Sb)2Te3, the search for the magnetic coupling mechanisms underlying the onset of ferromagnetism has been a central issue, and a variety of different scenarios have been put forward. By combining resonant photoemission, X-ray magnetic circular dichroism and density functional theory, we determine the local electronic and magnetic configurations of V and Cr impurities in (Bi,Sb)2Te3. State-of-the-art first-principles calculations find pronounced differences in their 3d densities of states, and show how these impurity states mediate characteristic short-range pd exchange interactions, whose strength sensitively varies with the position of the 3d states relative to the Fermi level. Measurements on films with varying host stoichiometry support this trend. Our results explain, in an unified picture, the origins of the observed magnetic properties, and establish the essential role of impurity-state-mediated exchange interactions in the magnetism of MTI.

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Contributing Institute(s):

1. Quanten-Theorie der Materialien (IAS-1)
2. Quanten-Theorie der Materialien (PGI-1)
3. JARA-FIT (JARA-FIT)
4. JARA - HPC (JARA-HPC)

Research Program(s):

1. 142 - Controlling Spin-Based Phenomena (POF3-142) (POF3-142)
2. 143 - Controlling Configuration-Based Phenomena (POF3-143) (POF3-143)

Appears in the scientific report 2020

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