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  - 
TY  - JOUR
A1  - Fiedler, Sebastian
A1  - El-Kareh, Lydia
A1  - Eremeev, Sergey V.
A1  - Tereshchenko, Oleg E.
A1  - Seibel, Christoph
A1  - Lutz, Peter
A1  - Kokh, Konstantin A.
A1  - Chulkov, Evgueni V.
A1  - Kuznetsova, Tatyana V.
A1  - Grebennikov, Vladimir I.
A1  - Bentmann, Hendrik
A1  - Bode, Matthias
A1  - Reinert, Friedrich
T1  - Defect and structural imperfection effects on the electronic properties of BiTeI surfaces
JF  - New Journal of Physics
N2  - 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.
KW  - electronic structure
KW  - spin–orbit coupling
KW  - surface morphology
KW  - semiconductor surfaces
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119467
SN  - 1367-2630
VL  - 16
IS  - 075013
ER  - 
TY  - JOUR
A1  - Sessi, Paolo
A1  - Silkin, Vyacheslav M.
A1  - Nechaev, Ilya A.
A1  - Bathon, Thomas
A1  - El-Kareh, Lydia
A1  - Chulkov, Evgueni V.
A1  - Echenique, Pedro M.
A1  - Bode, Matthias
T1  - Direct observation of many-body charge density oscillations in a two-dimensional electron gas
JF  - Nature Communications
N2  - Quantum interference is a striking manifestation of one of the basic concepts of quantum mechanics: the particle-wave duality. A spectacular visualization of this effect is the standing wave pattern produced by elastic scattering of surface electrons around defects, which corresponds to a modulation of the electronic local density of states and can be imaged using a scanning tunnelling microscope. To date, quantum-interference measurements were mainly interpreted in terms of interfering electrons or holes of the underlying band-structure description. Here, by imaging energy-dependent standing-wave patterns at noble metal surfaces, we reveal, in addition to the conventional surface-state band, the existence of an 'anomalous' energy band with a well-defined dispersion. Its origin is explained by the presence of a satellite in the structure of the many-body spectral function, which is related to the acoustic surface plasmon. Visualizing the corresponding charge oscillations provides thus direct access to many-body interactions at the atomic scale.
KW  - scanning tunneling spectroscopy
KW  - acoustic surface plasmon
KW  - metal surfaces
KW  - Cu(111)
KW  - excitations
KW  - microscopy
KW  - local density
KW  - standing wave formation
KW  - states
KW  - steps
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-145246
VL  - 6
IS  - 8691
ER  -