In: Physical Review B, 2015, vol. 92, no. 8, p. 081101
We present a detailed low-temperature scanning tunneling microscopy (STM) study of the commensurate charge density wave (CDW) in $1T-{\mathrm{TiSe}}_{2}$ in the presence of single atom defects. We find no significant modification of the CDW lattice in single crystals with native defect concentrations where some bulk probes already measure substantial reductions in the CDW phase transition...
|
In: Surface Science, 2015, vol. 639, p. 39-42
We report on the deposition of sub-monolayer Ag on the Si(331)–(12 × 1) surface. The growth of one-dimensional Ag nanostructures is observed by means of low- temperature scanning tunneling microscopy and low energy electron diffraction. We find that the deposited Ag is organized in nanostructures consistently taking “sawtooth” shapes. While the structures are not perfectly organized,...
|
In: Physical Review B, 2015, vol. 91, no. 16, p. 161410
We report layer-resolved measurements of the unoccupied electronic structure of ultrathin MgO films grown on Ag(001). The metal-induced gap states at the metal/oxide interface, the oxide band gap, and a surface core exciton involving an image-potential state of the vacuum are revealed through resonant Auger spectroscopy of the MgKL23L23 Auger transition. Our results demonstrate how to obtain new...
|
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: 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: 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: Journal of Physics: Condensed Matter, 2011, vol. 23, no. 13, p. 135003
Using angle-resolved photoelectron spectroscopy we investigate the electronic valence band structure of the Si(331)-(12 × 1) surface reconstruction for which we recently proposed a structural model containing silicon pentamers as elementary structural building blocks. We find that this surface, reported to be metallic in a previous study, shows a clear band gap at the Fermi energy, indicating...
|
In: Europhysics Letters, 2010, vol. 92, no. 4, p. 47003
We present angle-resolved photoemission experiments on 1T-TiSe₂ at temperatures ranging from 13 K to 288 K. The data evidence a dramatic renormalization of the conduction band below 100 K, whose origin can be related to the new potential responsible for the charge density wave phase at low temperature in this system. The renormalization translates into a substantial effective mass...
|
In: Physical Review B, 2010, vol. 81, no. 15, p. 1551104
The charge-density-wave phase transition of 1T-TiSe₂ is studied by angle-resolved photoemission over a wide temperature range. An important chemical-potential shift which strongly evolves with temperature is evidenced. In the framework of the exciton condensate phase, the detailed temperature dependence of the associated order parameter is extracted. Having a mean-field-like behavior at low...
|
In: Physica B: Condensed Matter, 2009, vol. 404, no. 19, p. 3172-3175
Recently, detailed calculations of the excitonic insulator phase model adapted to the case of 1T-TiSe2 have been presented. Through the spectral function theoretical photoemission intensity maps can be generated which are in very good agreement with experiment [H. Cercellier, et al., Phys. Rev. Lett. 99 (2007) 146403]. In this model, excitons condensate in a BCS-like manner and give rise to a...
|
