Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen OPUS4-17376 Wissenschaftlicher Artikel Maaß, Henriette; Bentmann, Hendrik; Seibel, Christoph; Tusche, Christian; Eremeev, Sergey V.; Peixoto, Thiago R.F.; Tereshchenko, Oleg E.; Kokh, Konstantin A.; Chulkov, Evgueni V.; Kirschner, Jürgen; Reinert, Friedrich Spin-texture inversion in the giant Rashba semiconductor BiTeI 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. 2016 Nature Communications 7 urn:nbn:de:bvb:20-opus-173769 10.1038/ncomms11621 Physikalisches Institut OPUS4-11946 Wissenschaftlicher Artikel Fiedler, Sebastian; El-Kareh, Lydia; Eremeev, Sergey V.; Tereshchenko, Oleg E.; Seibel, Christoph; Lutz, Peter; Kokh, Konstantin A.; Chulkov, Evgueni V.; Kuznetsova, Tatyana V.; Grebennikov, Vladimir I.; Bentmann, Hendrik; Bode, Matthias; Reinert, Friedrich Defect and structural imperfection effects on the electronic properties of BiTeI surfaces The surface electronic structure of the narrow-gap seminconductor BiTeI exhibits a large Rashba-splitting which strongly depends on the surface termination. Here we report on a detailed investigation of the surface morphology and electronic properties of cleaved BiTeI single crystals by scanning tunneling microscopy, photoelectron spectroscopy (ARPES, XPS), electron diffraction (SPA-LEED) and density functional theory calculations. Our measurements confirm a previously reported coexistence of Te- and I-terminated surface areas originating from bulk stacking faults and find a characteristic length scale of ~100 nm for these areas. We show that the two terminations exhibit distinct types of atomic defects in the surface and subsurface layers. For electronic states resided on the I terminations we observe an energy shift depending on the time after cleavage. This aging effect is successfully mimicked by depositon of Cs adatoms found to accumulate on top of the I terminations. As shown theoretically on a microscopic scale, this preferential adsorbing behaviour results from considerably different energetics and surface diffusion lengths at the two terminations. Our investigations provide insight into the importance of structural imperfections as well as intrinsic and extrinsic defects on the electronic properties of BiTeI surfaces and their temporal stability. 2014 New Journal of Physics 16 075013 urn:nbn:de:bvb:20-opus-119467 10.1088/1367-2630/16/7/075013 Physikalisches Institut OPUS4-11278 Wissenschaftlicher Artikel El-Kareh, Lydia; Bihlmayer, Gustav; Buchter, Arne; Bentmann, Hendrik; Blügel, Stefan; Reinert, Friedrich; Bode, Matthias A combined experimental and theoretical study of Rashba-split surface states on the ( √3x√3) Pb/Ag (111)R30° surface 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. 2014 urn:nbn:de:bvb:20-opus-112786 doi:10.1088/1367-2630/16/4/045017 Physikalisches Institut OPUS4-12972 Wissenschaftlicher Artikel Bentmann, Hendrik; Reinert, Friedrich Enhancing and reducing the Rashba-splitting at surfaces by adsorbates: Na and Xe on Bi/Cu(111) The surface alloy Bi/Cu(111) shows a paradigmatic free-electron-like surface state with a very large Rashba-type spin-orbit splitting. Using angle-resolved photoemission we investigate how adsorbates of different chemical nature influence the size of the spin splitting in this system. We find that the adsorption of small amounts of monovalent Na atoms leads to an enhancement of the spin splitting while an overlayer of the closed-shell rare gas Xe causes a reduction. The latter result is in contrast to the Au(111) surface for which an increased splitting size after Xe-adsorption was observed. We discuss these experimental findings in terms of the characteristic differences of the surface state wave functions and their spatial deformation in the presence of different types of adsorbates. Our results provide insight into the complex interplay of atomic and interface potential gradients governing the Rashba effect. 2013 New Journal of Physics 15 115011 urn:nbn:de:bvb:20-opus-129722 10.1088/1367-2630/15/11/115011 Physikalisches Institut