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Université de Neuchâtel

Use of angle-resolved photoemission and density functional theory for surface structural analysis of YSi2

Koitzsch, Christian ; Bovet, M. ; Garnier, Michael Bernard Gunnar ; Aebi, Philipp ; Rogero, C. ; Martín-Gago, J. A.

In: Surface Science, 2004, vol. 566-568, no. 2, p. 1047-1051

The atomic structure of two-dimensional yttrium silicide epitaxially grown on Si(1 1 1) was investigated by means of density functional theory calculations and angle-resolved photoemission experiments. The obtained accuracy of the calculations allowed to discriminate different surface arrangements in a quantitative way via comparing their theoretical band structure to the experimental result....

Université de Neuchâtel

Electronic structure of ZrTe3

Starowicz, P. ; Battaglia, Corsin ; Clerc, F. ; Despont, Laurent ; Prodan, A. ; van Midden, H. J. P. ; Szerer, U. ; Szytuła, A. ; Garnier, Michael Bernard Gunnar ; Aebi, Philipp

In: Journal of Alloys and Compounds, 2007, vol. 442, no. 1-2, p. 268-271

The Fermi surface topology of the layered superconducting charge density wave compound ZrTe3 is investigated by angle resolved photoelectron spectroscopy and density functional theory. The Fermi surface is dominated by bands originating from two perpendicular systems of quasi one-dimensional chains. Nesting and opening of a pseudogap at temperatures as high as 250 K are signatures of a...

Université de Neuchâtel

Structural investigations of epitaxial InN by x-ray photoelectron diffraction and x-ray diffraction

Hofstetter, Daniel ; Despont, Laurent ; Garnier, Michael Bernard Gunnar ; Baumann, Esther ; Giorgetta, Fabrizio R. ; Aebi, Philipp ; Kirste, Lutz ; Lu, Hai ; Schaff, William J.

In: Applied Physics Letters, 2007, vol. 90, no. 191912, p. 1-3

The authors investigated a 1 µm thick molecular beam epitaxy–grown InN film by means of full hemispherical x-ray photoelectron diffraction and high resolution x-ray diffraction. While x-ray diffraction reveals that this nominally hexagonal InN layer contains roughly 1% of cubic phase InN, a comparison between measured and simulated x-ray photoelectron diffraction data allowed them to...

Université de Neuchâtel

Monodomain to polydomain transition in ferroelectric PbTiO3 thin films with La0.67Sr0.33MnO3 electrodes

Lichtensteiger, Céline ; Dawber, Matthew ; Stucki, Nicolas ; Triscone, Jean-Marc ; Hoffman, Jason ; Yau, Jeng-Bang ; Ahn, Charles H. ; Despont, Laurent ; Aebi, Philipp

In: Applied Physics Letters, 2007, vol. 90, no. 052907, p. 1-3

Finite size effects in ferroelectric thin films have been probed in a series of epitaxial perovskite c-axis oriented PbTiO3 films grown on thin La0.67Sr0.33MnO3 epitaxial electrodes. The film thickness ranges from 480 down to 28 Å (seven unit cells). The evolution of the film tetragonality c/a, studied using high resolution x-ray diffraction...

Université de Neuchâtel

X-ray absorption fine structure studies of buried Ge-Si interfaces

Aebi, Philipp ; Tyliszczak, T. ; Hitchcock, A. P. ; Jackman, T. E. ; Baribeau, J.-M.

In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1991, vol. 9, no. 3, p. 907-911

We have used Ge A-edge x-ray absorption fine structure (EXAFS) and a gas ionization detector with sample rotation to study the local environment of nominally pure Qe layers buried in single crystal Si. The samples were grown by molecular-beam epitaxy on Si( 100). The dependence on thickness, number of Ge layers and growth temperature is explored. Considerable sensitivity to the quality of the...

Université de Neuchâtel

Preparation and characterization of clean, single-crystalline YHx films (0≤x≤2.9) on W(110)

Hayoz, J. ; Pillo, T. ; Bovet, M. ; Guthrie, St. ; Pastore, G. ; Schlapbach, Louis ; Aebi, Philipp

In: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 2000, vol. 18, no. 5, p. 2417-2431

Yttrium can be loaded with hydrogen up to high concentrations causing dramatic structural and electronic changes of the host lattice. We report on the preparation of clean, single-crystalline YHx films (0≤x≤2.9). The films have been characterized in situ combining angle-resolved photoelectron spectroscopy (ARPES) and low energy electron diffraction. Direct Y dihydride...

Université de Neuchâtel

Doping-dependent electronic structure of cuprates studied using angle-scanned photoemission

Schwaller, P. ; Greber, T. ; Aebi, Philipp ; Singer, J. M. ; Berger, H. ; Forró, L. ; Osterwalder, J.

In: The European Physical Journal B - Condensed Matter and Complex Systems, 2000, vol. 18, no. 2, p. 215-225

Full k ||-maps of the electronic structure near the Fermi level of differently doped cuprates measured with angle-scanned photoelectron spectroscopy are presented. The valence band maximum of the antiferromagnetic insulator Sr2CuO2Cl2, which is taken as a representative of an undoped cuprate, and the Fermi surfaces of overdoped, optimally doped and...

Université de Neuchâtel

Oxygen-segregation-controlled epitaxy of Y2O3 films on Nb(110)

Hayoz, J. ; Bovet, M. ; Pillo, T. ; Schlapbach, Louis ; Aebi, Philipp

In: Applied Physics A: Materials Science & Processing, 2000, vol. 71, no. 6, p. 615-618

We demonstrate a very simple and reliable method of manufacturing clean, single-crystalline Y2O3 films on Nb(110) substrates in situ. The method exploits the oxygen bulk contamination of Nb as a source of clean oxygen. For substrate temperatures above 800 K oxygen segregation to the Nb surface is so efficient, that yttrium becomes oxidized during deposition without any...

Université de Neuchâtel

Non-uniform doping across the Fermi surface of NbS2 intercalates

Battaglia, Corsin ; Cercellier, H. ; Despont, L. ; Monney, Claude ; Prester, M. ; Berger, H. ; Forró, L. ; Garnier, Michael Bernard Gunnar ; Aebi, Philipp

In: The European Physical Journal B - Condensed Matter and Complex Systems, 2007, vol. 57, no. 4, p. 385-390

Magnetic ordering of the first row transition metal intercalates of NbS2 due to coupling between the conduction electrons and the intercalated ions has been explained in terms of Fermi surface nesting. We use angle-resolved photoelectron spectroscopy to investigate the Fermi surface topology and the valence band structure of the quasi-two-dimensional layer compounds...

Université de Neuchâtel

Angle-scanned photoemission on YbHx: relevance for switchable mirrors

Hayoz, J. ; Koitzsch, C. ; Popovic, D. ; Bovet, M. ; Naumovic, D. ; Aebi, Philipp

In: Surface Review and Letters (SRL), 2002, vol. 9, no. 1, p. 235-241

Yttrium, lantanum and rare earth elements can be loaded with hydrogen inducing a metal–insulator transition and giving rise to optical switching from reflecting to transparent. We present angle-scanned photoemission experiments characterizing thin YbHx films grown on W(110) at room temperature. Hydrogen loading is performed in an ultrahigh-vacuum-compatible high pressure (1 bar)...