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 - TY - JOUR A1 - El-Kareh, Lydia A1 - Bihlmayer, Gustav A1 - Buchter, Arne A1 - Bentmann, Hendrik A1 - Blügel, Stefan A1 - Reinert, Friedrich A1 - Bode, Matthias T1 - A combined experimental and theoretical study of Rashba-split surface states on the ( √3x√3) Pb/Ag (111)R30° surface N2 - We report on a combined low-temperature scanning tunneling spectroscopy (STS), angle-resolved photoemission spectroscopy (ARPES), and density functional theory (DFT) investigation of the ( √3x√3) Pb/Ag (111)R30° surface alloy which provides a giant Rashba-type spin splitting. With STS we observed spectroscopic features that are assigned to two hole-like Rashba-split bands in the unoccupied energy range. By means of STS and quantum interference mapping we determine the band onsets, splitting strengths, and dispersions for both bands. The unambiguous assignment of scattering vectors is achieved by comparison to ARPES measurements. While intra-band scattering is found for both Rashba bands, inter-band scattering is only observed in the occupied energy range. Spin- and orbitally-resolved band structures were obtained by DFT calculations. Considering the scattering between states of different spin- and orbital character, the apparent deviation between experimentally observed scattering events and the theoretically predicted spin polarization could be resolved. KW - Rashba effect KW - spin–orbit coupling KW - scanning tunneling microscopy KW - angle resolved photo emission spectroscopy KW - density functional theory Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-112786 ER -