In: Surface Science, 2006, vol. 351, no. 3-4, p. 245-249
The transition metal dichalcogenide 1T-TaS2 is a layered material exhibiting charge density waves. Based on angle-resolved photoemission experiments mapping spectral weight at the Fermi surface and density functional theory calculations we discuss possible mechanisms involved with the creation of charge density waves. At first the flat parts of the elliptically shaped Fermi...
|
In: Surface Science, 2006, vol. 600, no. 2, p. 380-385
Multiple scattering theory based on a cluster model is used to simulate full-hemispherical X-ray photoelectron diffraction measurements in order to verify how state of the art multiple scattering simulations are able to reproduce the experiment. This approach is applied to the Cu(1 1 1) surface for two different photoelectron kinetic energies. Differences and similarities between single and...
|
In: Physical Review B, 2004, vol. 70, no. 165114, p. 1-10
We report high-resolution angle-resolved photoemission experiments on epitaxial thin films of different rare-earth (RE) dihydrides (RE=Gd,La) and of YH2 and ScH2 . It is found through ab initio calculations and confirmed by Fermi surface mapping that the electronic structure becomes very similar upon hydrogenation, rendering the studied dihydrides...
|
In: Physical Review B, 2005, vol. 95, no. 126401, p. 1-4
Quantum well states are a consequence of confinement in a quantum cavity. In this study we investigate with photoemission the influence of the interface electronic structure on the quantum well state energy dispersion in ultrathin Mg(0001) films on W (110). Coupling between the sp-derived quantum well states and the substrate across the interface becomes manifest in a deviation from...
|
In: Despont, Laurent ; Institut de Physique, Université de Neuchâtel, Switzerland, 2006, vol. 73, no. 094110, p. 1-6
X-ray photoelectron diffraction is used to directly probe the intracell polar atomic distortion and tetragonality associated with ferroelectricity in ultrathin epitaxial PbTiO3 films. Our measurements, combined with ab initio calculations, unambiguously demonstrate noncentrosymmetry in films a few unit cells thick, imply that films as thin as three unit cells still preserve a...
|
In: Physical Review B, 2006, vol. 74, no. 155114, p. 1-7
The temperature dependence of the electronic structure of the quasi-two-dimensional material 1T-TaS2 is revisited by considering angle-resolved photoemission spectroscopy (ARPES) and density functional theory to calculate the imaginary part of the static electronic susceptibility characterizing the nesting strength. While nesting appears to play a role in the high temperature...
|
In: Physical Review B, 2005, vol. 72, no. 195114, p. 1-10
The origin of the monoclinic distortion and domain formation in the quasi-two-dimensional layer compound NbTe2 is investigated. Angle-resolved photoemission shows that the Fermi surface is pseudogapped over large portions of the Brillouin zone. Ab initio calculation of the electron and phonon band structure as well as the static RPA susceptibility lead us to conclude that Fermi...
|
In: Physical Review Letters, 2007, vol. 99, no. 146403, p. 1-4
We present a new high-resolution angle-resolved photoemission study of 1T–TaS2 in both its room-temperature, normal phase and its low-temperature, charge-density wave phase. At low temperature the photoemission spectra are strongly modified, with large band renormalizations at high-symmetry points of the Brillouin zone and a very large transfer of spectral weight to backfolded...
|
In: The European Physical Journal B - Condensed Matter and Complex Systems, 2006, vol. 52, no. 3, p. 421-426
Multiple scattering theory based on a cluster model is used to simulate full hemispherical X-ray photoelectron diffraction measurements on a 1T-TaS2 (0001) surface. Key points to determine the surface termination are discussed. As the commonly applied single scattering simulations do not give satisfying results, a multiple scattering approach has to be used to accurately...
|
In: European Physical Journal B (The) - Condensed Matter and Complex Systems, 2006, vol. 49, no. 2, p. 141-146
Full hemispherical X-ray photoelectron diffraction (XPD) experiments have been performed to investigate at the atomic level ultrathin epitaxial c-axis oriented PbTiO3 (PTO) films grown on Nb-doped SrTiO3 substrates. Comparison between experiment and theory allows us to identify a preferential ferroelectric polarization state in a 60 Å -thick PTO film. Multiple scattering...
|
