359 research outputs found
Inelastic Decay of Electrons in the Shockley-type Metal-Organic Interface States
We present a theoretical study of lifetimes of interface states (IS) on
metal-organic interfaces PTCDA/Ag(111), NTCDA/Ag(111), PFP/Ag(111), and
PTCDA/Ag(100), describing and explaining the recent experimental data. By means
of unfolding the band structure of one of the interfaces under study onto the
Ag(111) Brillouin zone we demonstrate, that the Brillouin zone folding upon
organic monolayer deposition plays a minor role in the phase space for electron
decay, and hence weakly affects the resulting lifetimes. The presence of the
unoccupied molecular states below the IS gives a small contribution to the IS
decay rate mostly determined by the change of the phase space of bulk states
upon the energy shift of the IS. The calculated lifetimes follow the
experimentally observed trends. In particular, we explain the trend of the
unusual increase of the IS lifetimes with rising temperature.Comment: 8 pages, 5 figure
Magnetic proximity effect at the 3D topological insulator/magnetic insulator interface
The magnetic proximity effect is a fundamental feature of heterostructures
composed of layers of topological insulators and magnetic materials since it
underlies many potential applications in devices with novel quantum
functionality. Within density functional theory we study magnetic proximity
effect at the 3D topological insulator/magnetic insulator (TI/MI) interface in
BiSe/MnSe(111) system as an example. We demonstrate that a gapped
ordinary bound state which spectrum depends on the interface potential arises
in the immediate region of the interface. The gapped topological Dirac state
also arises in the system owing to relocation to deeper atomic layers of
topological insulator. The gap in the Dirac cone is originated from an
overlapping of the topological and ordinary interfacial states. This result
being also corroborated by the analytic model, is a key aspect of the magnetic
proximity effect mechanism in the TI/MI structures.Comment: 10 pages, 3 figure
Band bending driven evolution of the bound electron states at the interface between a three-dimensional topological insulator and a three-dimensional normal insulator
In the frame of k⋅p method and variational approach for the effective energy functional of a contact between a three-dimensional topological insulator (TI) and normal insulator (NI), we analytically describe the formation of interfacial bound electron states of two types (ordinary and topological) having different spatial distributions and energy spectra. We show that these states appear as a result of the interplay of two factors: hybridization and band bending of the TI and NI electron states near the TI/NI boundary. These results are corroborated by the density functional theory calculations for the exemplar Bi2Se3/ZnSe system
Role of bulk and surface phonons in the decay of metal surface states
We present a comprehensive theoretical investigation of the electron-phonon
contribution to the lifetime broadening of the surface states on Cu(111) and
Ag(111), in comparison with high-resolution photoemission results. The
calculations, including electron and phonon states of the bulk and the surface,
resolve the relative importance of the Rayleigh mode, being dominant for the
lifetime at small hole binding energies. Including the electron-electron
interaction, the theoretical results are in excellent agreement with the
measured binding energy and temperature dependent lifetime broadening.Comment: 4 pages, 3 figure
Image states in metal clusters
The existence of image states in small clusters is shown, using a quantum-mechanical many-body approach. We present image state energies and wave functions for spherical jellium clusters up to 186 atoms, calculated in the GW approximation, where G is the Green's function and W is the dynamically screened Coulomb interaction, which by construction contains the dynamic long-range correlation effects that give rise to image effects. In addition, we find that image states are also subject to quantum confinement. To extrapolate our investigations to clusters in the mesoscopic size range, we propose a semiclassical model potential, which we test against our full GW results
Excited states of Na nanoislands on the Cu(111) surface
Electronic states of one monolayer high Na nanoislands on the Cu(111) surface are studied as a function of the nanoisland size. Properties of nanoislands such as one-electron states, the electron density, and the associated potential are obtained self-consistently within the density-functional formalism using a one-dimensional pseudopotential for the Cu(111) substrate and the jellium model for Na. A wave packet propagation method is used to study the energies and lifetimes of quasistationary states localized at Na islands. For very large islands, island-localized states merge into the two-dimensional continuum of the Na quantum well state. Thus, we assign the quasistationary states studied as arising from the quantization of the two-dimensional quantum well continuum due to the finite island size. The scattering at the island boundaries results in the energy-conserving resonant electron transfer into the continuum of the substrate states broadening the island-localized states into resonances.Peer reviewe
- …