In: Physical Review Letters, 2014, vol. 112, no. 19, p. 197001
The transition-metal dichalcogenide 1T−TiSe₂is a quasi-two-dimensional layered material with a charge density wave (CDW) transition temperature of TCDW≈200 K. Self-doping effects for crystals grown at different temperatures introduce structural defects, modify the temperature-dependent resistivity, and strongly perturbate the CDW phase. Here, we study the structural and doping nature...
|
In: Physical Review B - Condensed Matter and Materials Physics, 2012, vol. 86, no. 19, p. 195147
We investigate the behavior of the spectral weight near the Fermi level of NdNiO3 thin films as a function of temperature across the metal-to-insulator transition (MIT) by means of ultraviolet photoelectron spectroscopy. The spectral weight was found to exhibit thermal hysteresis, similar to that of the dc conductivity. A detailed analysis of the temperature dependence reveals two distinct...
|
In: Surface Science, 2012, p. -
The electronic structure of the TiO₂ (110)-(1 × 2) surface has been studied by means of angular resolved ultraviolet photoemission spectroscopy (ARUPS). The valence band dispersion along the high symmetry surface directions, [001] and [1–10], has been recorded. The experimental data show no dispersion of the band-gap Ti 3d states. However, the existence of dispersive bands along the [001]...
|
In: Journal of Materials Science, 2012, p. -
Misfit-layered Ca₃Co₄O₉ crystals were grown and characterized via XRD, SEM, and photo-emission spectroscopy (PES). The evolution of the intensity at the Fermi level (E F) with varying oxygen content was studied by PES. Oxygen species were successfully introduced and removed through O⁺ and H⁺ microwave-plasma (2.45 GHz, 2–5 mbar) treatments, respectively. A 5 min...
|
In: Physical Review B - Condensed Matter and Materials Physics, 2012, vol. 85, no. 23, p. 235150
To address the fluctuation regime above the critical temperature of the charge-density-wave phase of 1T-TiSe₂, we perform calculations using the Bethe-Salpeter equation for treating strong electron-hole correlations. Calculated photoemission intensity maps are in good agreement with the measured ones and provide a deeper understanding of the phase transition in terms of an electronic...
|
In: Surface Science, 2012, vol. 606, no. 23-24, p. 1755-1759
Since more than twenty years it is known that deposition of Ag onto Si(111)–(7 × 7) leads under certain conditions to the formation of so-called “ring-like” clusters, that are particularly stable among small clusters. In order to resolve their still unknown atomic structure, we performed voltage dependent scanning tunneling microscopy (STM) measurements providing interesting...
|
In: Physical Review Letters, 2012, vol. 109, p. 047401
In high-resolution resonant inelastic x-ray scattering at the Ti L edge of the charge-density-wave system 1T-TiSe₂, we observe sharp low energy loss peaks from electron-hole pair excitations developing at low temperature. These excitations are strongly dispersing as a function of the transferred momentum of light. We show that the unoccupied bands close to the Fermi level can effectively be...
|
In: Physical Review B - Condensed matter and materials physics, 2012, vol. 85, no. 19, p. 195111
We present both theoretical ab-initio results within the Hedin's GW approximation and experimental angle-resolved photoemission and scanning tunneling spectroscopy measurements on TiSe₂. With respect to the density-functional Kohn-Sham metallic picture, the many-body GW self-energy leads to a ≈0.2-eV band-gap insulator consistent with our STS spectra at 5 K. The highest valence and the lowest...
|
In: The European Physical Journal B - Condensed Matter And Complex Systems, 2011, vol. 81, no. 4, p. 399-403
We explore the interplay between the elastic scattering of photoelectrons and the surface core level shifts with regard to the determination of core level binding energies in Au(111) and Cu3Au(100). We find that an artificial shift is created in the binding energies of the Au 4f core levels, that exhibits a dependence on the emission angle, as well as on the spectral intensity of the core...
|
In: Physical Review Letters, 2011, vol. 106, no. 10, p. 106404
We address the lattice deformation of 1T-TiSe₂ within the exciton condensate phase. We show that, at low temperature, condensed excitons influence the lattice through electron-phonon interaction. It is found that at zero temperature, in the exciton condensate phase of 1T-TiSe₂, this exciton condensate exerts a force on the lattice generating ionic displacements comparable in amplitude to what...
|
