440 research outputs found
Simultaneous quantization of bulk conduction and valence states through adsorption of nonmagnetic impurities on Bi2Se3
Exposing the (111) surface of the topological insulator Bi2Se3 to carbon
monoxide results in strong shifts of the features observed in angle-resolved
photoemission. The behavior is very similar to an often reported `aging' effect
of the surface and it is concluded that this aging is most likely due to the
adsorption of rest gas molecules. The spectral changes are also similar to
those recently reported in connection with the adsorption of the magnetic
adatom Fe. All spectral changes can be explained by a simultaneous confinement
of the conduction band and valence band states. This is only possible because
of the unusual bulk electronic structure of Bi2Se3. The valence band
quantization leads to spectral features which resemble those of a band gap
opening at the Dirac point.Comment: 5 pages, 4 figure
Intra- and Interband Electron Scattering in the Complex Hybrid Topological Insulator Bismuth Bilayer on BiSe
The band structure, intra- and interband scattering processes of the
electrons at the surface of a bismuth-bilayer on BiSe have been
experimentally investigated by low-temperature Fourier-transform scanning
tunneling spectroscopy. The observed complex quasiparticle interference
patterns are compared to a simulation based on the spin-dependent joint density
of states approach using the surface-localized spectral function calculated
from first principles as the only input. Thereby, the origin of the
quasiparticle interferences can be traced back to intraband scattering in the
bismuth bilayer valence band and BiSe conduction band, and to interband
scattering between the two-dimensional topological state and the
bismuth-bilayer valence band. The investigation reveals that the bilayer band
gap, which is predicted to host one-dimensional topological states at the edges
of the bilayer, is pushed several hundred milli-electronvolts above the Fermi
level. This result is rationalized by an electron transfer from the bilayer to
BiSe which also leads to a two-dimensional electron state in the
BiSe conduction band with a strong Rashba spin-splitting, coexisting
with the topological state and bilayer valence band.Comment: 11 pages, 5 figure
A Helium-Surface Interaction Potential of BiTe(111) from Ultrahigh-Resolution Spin-Echo Measurements
We have determined an atom-surface interaction potential for the
HeBiTe(111) system by analysing ultrahigh resolution measurements of
selective adsorption resonances. The experimental measurements were obtained
using He spin-echo spectrometry. Following an initial free-particle model
analysis, we use elastic close-coupling calculations to obtain a
three-dimensional potential. The three-dimensional potential is then further
refined based on the experimental data set, giving rise to an optimised
potential which fully reproduces the experimental data. Based on this analysis,
the HeBiTe(111) interaction potential can be described by a
corrugated Morse potential with a well depth , a
stiffness and a surface electronic
corrugation of % of the lattice constant. The improved
uncertainties of the atom-surface interaction potential should also enable the
use in inelastic close-coupled calculations in order to eventually study the
temperature dependence and the line width of selective adsorption resonances
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