1,164 research outputs found
Preputial surgery in the bull
Call number: LD2668 .T4 1979 B67Master of Scienc
Interlayer interaction and electronic screening in multilayer graphene
The unusual transport properties of graphene are the direct consequence of a
peculiar bandstructure near the Dirac point. We determine the shape of the pi
bands and their characteristic splitting, and the transition from a pure 2D to
quasi-2D behavior for 1 to 4 layers of graphene by angle-resolved
photoemission. By exploiting the sensitivity of the pi bands to the electronic
potential, we derive the layer-dependent carrier concentration, screening
length and strength of interlayer interaction by comparison with tight binding
calculations, yielding a comprehensive description of multilayer graphene's
electronic structure
Morphology of graphene thin film growth on SiC(0001)
Epitaxial films of graphene on SiC(0001) are interesting from a basic physics
as well as applications-oriented point of view. Here we study the emerging
morphology of in-vacuo prepared graphene films using low energy electron
microscopy (LEEM) and angle-resolved photoemission (ARPES). We obtain an
identification of single and bilayer of graphene film by comparing the
characteristic features in electron reflectivity spectra in LEEM to the PI-band
structure as revealed by ARPES. We demonstrate that LEEM serves as a tool to
accurately determine the local extent of graphene layers as well as the layer
thickness
Massive enhancement of electron-phonon coupling in doped graphene by an electronic singularity
The nature of the coupling leading to superconductivity in layered materials
such as high-Tc superconductors and graphite intercalation compounds (GICs) is
still unresolved. In both systems, interactions of electrons with either
phonons or other electrons or both have been proposed to explain
superconductivity. In the high-Tc cuprates, the presence of a Van Hove
singularity (VHS) in the density of states near the Fermi level was long ago
proposed to enhance the many-body couplings and therefore may play a role in
superconductivity. Such a singularity can cause an anisotropic variation in the
coupling strength, which may partially explain the so-called nodal-antinodal
dichotomy in the cuprates. Here we show that the topology of the graphene band
structure at dopings comparable to the GICs is quite similar to that of the
cuprates and that the quasiparticle dynamics in graphene have a similar
dichotomy. Namely, the electron-phonon coupling is highly anisotropic,
diverging near a saddle point in the graphene electronic band structure. These
results support the important role of the VHS in layered materials and the
possible optimization of Tc by tuning the VHS with respect to the Fermi level.Comment: 8 page
Quasiparticle Transformation During a Metal-Insulator Transition in Graphene
Here we show, with simultaneous transport and photoemission measurements,
that the graphene terminated SiC(0001) surface undergoes a metal-insulator
transition (MIT) upon dosingwith small amounts of atomic hydrogen. We find the
room temperature resistance increases by about 4 orders of magnitude, a
transition accompanied by anomalies in the momentum-resolved spectral function
including a non-Fermi Liquid behaviour and a breakdown of the quasiparticle
picture. These effects are discussed in terms of a possible transition to a
strongly (Anderson) localized ground state.Comment: 11 pages, 4 figure
Brief of Kaiser Permanente as Amicus Curiae in Support of Petitioners
Brief of Amici Curiae ("friend of the court") submitted by Kaiser Permanente in support of petitioners on petition for a Writ of Certiorari (No. 11-725
Antipsychotic‐Induced Hyperprolactinemia
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90238/1/phco.29.1.64.pd
Tunable Polaronic Conduction in Anatase TiO2
Oxygen vacancies created in anatase TiO2 by UV photons (80–130 eV) provide an effective electron-doping mechanism and induce a hitherto unobserved dispersive metallic state. Angle resolved photoemission reveals that the quasiparticles are large polarons. These results indicate that anatase can be tuned from an insulator to a polaron gas to a weakly correlated metal as a function of doping and clarify the nature of conductivity in this material.open1192sciescopu
Strictly One-Dimensional Electron System in Au Chains on Ge(001) Revealed By Photoelectron K-Space Mapping
Atomic nanowires formed by Au on Ge(001) are scrutinized for the band
topology of the conduction electron system by k-resolved photoemission. Two
metallic electron pockets are observed. Their Fermi surface sheets form
straight lines without undulations perpendicular to the chains within
experimental uncertainty. The electrons hence emerge as strictly confined to
one dimension. Moreover, the system is stable against a Peierls distortion down
to 10 K, lending itself for studies of the spectral function. Indications for
unusually low spectral weight at the chemical potential are discussed.Comment: 4 pages, 4 figures - revised version with added Fig. 2e) and
additional reference
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