TY  - JOUR
A1  - Maaß, Henriette
A1  - Bentmann, Hendrik
A1  - Seibel, Christoph
A1  - Tusche, Christian
A1  - Eremeev, Sergey V.
A1  - Peixoto, Thiago R.F.
A1  - Tereshchenko, Oleg E.
A1  - Kokh, Konstantin A.
A1  - Chulkov, Evgueni V.
A1  - Kirschner, Jürgen
A1  - Reinert, Friedrich
T1  - Spin-texture inversion in the giant Rashba semiconductor BiTeI
JF  - Nature Communications
N2  - Semiconductors with strong spin–orbit interaction as the underlying mechanism for the generation of spin-polarized electrons are showing potential for applications in spintronic devices. Unveiling the full spin texture in momentum space for such materials and its relation to the microscopic structure of the electronic wave functions is experimentally challenging and yet essential for exploiting spin–orbit effects for spin manipulation. Here we employ a state-of-the-art photoelectron momentum microscope with a multichannel spin filter to directly image the spin texture of the layered polar semiconductor BiTeI within the full two-dimensional momentum plane. Our experimental results, supported by relativistic ab initio calculations, demonstrate that the valence and conduction band electrons in BiTeI have spin textures of opposite chirality and of pronounced orbital dependence beyond the standard Rashba model, the latter giving rise to strong optical selection-rule effects on the photoelectron spin polarization. These observations open avenues for spin-texture manipulation by atomic-layer and charge carrier control in polar semiconductors.
KW  - applied physics
KW  - spintronics
KW  - semiconductors
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-173769
VL  - 7
ER  - 
TY  - JOUR
A1  - Peixoto, Thiago R. F.
A1  - Bentmann, Hendrik
A1  - Rüßmann, Philipp
A1  - Tcakaev, Abdul-Vakhab
A1  - Winnerlein, Martin
A1  - Schreyeck, Steffen
A1  - Schatz, Sonja
A1  - Vidal, Raphael Crespo
A1  - Stier, Fabian
A1  - Zabolotnyy, Volodymyr
A1  - Green, Robert J.
A1  - Min, Chul Hee
A1  - Fornari, Celso I.
A1  - Maaß, Henriette
A1  - Vasili, Hari Babu
A1  - Gargiani, Pierluigi
A1  - Valvidares, Manuel
A1  - Barla, Alessandro
A1  - Buck, Jens
A1  - Hoesch, Moritz
A1  - Diekmann, Florian
A1  - Rohlf, Sebastian
A1  - Kalläne, Matthias
A1  - Rossnagel, Kai
A1  - Gould, Charles
A1  - Brunner, Karl
A1  - Blügel, Stefan
A1  - Hinkov, Vladimir
A1  - Molenkamp, Laurens W.
A1  - Friedrich, Reinert
T1  - Non-local effect of impurity states on the exchange coupling mechanism in magnetic topological insulators
JF  - NPJ Quantum Materials
N2  - Since the discovery of the quantum anomalous Hall (QAH) effect in the magnetically doped topological insulators (MTI) Cr:(Bi,Sb)\(_2\)Te\(_3\) and V:(Bi,Sb)\(_2\)Te\(_3\), 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)\(_2\)Te\(_3\). 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.
KW  - shape-truncation functions
KW  - semiconductors
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-230686
VL  - 5
ER  -