@article{MaassBentmannSeibeletal.2016, author = {Maaß, Henriette and Bentmann, Hendrik and Seibel, Christoph and Tusche, Christian and Eremeev, Sergey V. and Peixoto, Thiago R.F. and Tereshchenko, Oleg E. and Kokh, Konstantin A. and Chulkov, Evgueni V. and Kirschner, J{\"u}rgen and Reinert, Friedrich}, title = {Spin-texture inversion in the giant Rashba semiconductor BiTeI}, series = {Nature Communications}, volume = {7}, journal = {Nature Communications}, doi = {10.1038/ncomms11621}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173769}, year = {2016}, abstract = {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.}, language = {en} } @article{PollingerSchmittSanderetal.2017, author = {Pollinger, Florian and Schmitt, Stefan and Sander, Dirk and Tian, Zhen and Kirschner, J{\"u}rgen and Vrdoljak, Pavo and Stadler, Christoph and Maier, Florian and Marchetto, Helder and Schmidt, Thomas and Sch{\"o}ll, Achim and Umbach, Eberhard}, title = {Nanoscale patterning, macroscopic reconstruction, and enhanced surface stress by organic adsorption on vicinal surfaces}, series = {New Journal of Physics}, volume = {19}, journal = {New Journal of Physics}, doi = {10.1088/1367-2630/aa55b8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171947}, year = {2017}, abstract = {Self-organization is a promising method within the framework of bottom-up architectures to generate nanostructures in an efficient way. The present work demonstrates that self- organization on the length scale of a few to several tens of nanometers can be achieved by a proper combination of a large (organic) molecule and a vicinal metal surface if the local bonding of the molecule on steps is significantly stronger than that on low-index surfaces. In this case thermal annealing may lead to large mass transport of the subjacent substrate atoms such that nanometer-wide and micrometer-long molecular stripes or other patterns are being formed on high-index planes. The formation of these patterns can be controlled by the initial surface orientation and adsorbate coverage. The patterns arrange self-organized in regular arrays by repulsive mechanical interactions over long distances accompanied by a significant enhancement of surface stress. We demonstrate this effect using the planar organic molecule PTCDA as adsorbate and Ag(10 8 7) and Ag(775)surfaces as substrate. The patterns are directly observed by STM, the formation of vicinal surfaces is monitored by highresolution electron diffraction, the microscopic surface morphology changes are followed by spectromicroscopy, and the macroscopic changes of surface stress are measured by a cantilever bending method. The in situ combination of these complementary techniques provides compelling evidence for elastic interaction and a significant stress contribution to long-range order and nanopattern formation.}, language = {en} }