Université de Fribourg

Robustness of the charge-ordered phases in ${\mathrm{IrTe}}_{2}$ against photoexcitation

Monney, Claude ; Schuler, A. ; Jaouen, T. ; Mottas, Marie-Laure ; Wolf, Thomas ; Merz, M. ; Muntwiler, Matthias ; Castiglioni, L. ; Aebi, Philipp ; Weber, F. ; Hengsberger, M.

In: Physical Review B, 2018, vol. 97, no. 7, p. 075110

We present a time-resolved angle-resolved photoelectron spectroscopy study of IrTe2, which undergoes two first-order structural and charge-ordered phase transitions on cooling below 270 K and below 180 K. The possibility of inducing a phase transition by photoexcitation with near-infrared femtosecond pulses is investigated in the charge-ordered phases. We observe changes of the spectral...

Université de Fribourg

Tuning electronic correlations in transition metal pnictides: Chemistry beyond the valence count

Razzoli, Elia ; Matt, Christian E. ; Kobayashi, M. ; Wang, X.-P. ; Strocov, V. N. ; Roekeghem, A. van ; Biermann, Silke ; Plumb, N. C. ; Radovic, M. ; Schmitt, T. ; Capan, C. ; Fisk, Z. ; Richard, P. ; Ding, H. ; Aebi, Philipp ; Mesot, J. ; Shi, Ming

In: Physical Review B, 2015, vol. 91, no. 21, p. 214502

The effects of electron-electron correlations on the low-energy electronic structure and their relationship with unconventional superconductivity are central aspects in the research on iron-based pnictide superconductors. Here we use soft x-ray angle-resolved photoemission spectroscopy to study how electronic correlations evolve in different chemically substituted iron pnictides. We find that...

Université de Fribourg

Scanning tunneling microscopy of the charge density wave in $1T-{\mathrm{TiSe}}_{2}$ in the presence of single atom defects

Novello, Anna M. ; Hildebrand, Baptiste ; Scarfato, A. ; Didiot, Clément ; Monney, Gaël ; Ubaldini, A. ; Berger, Helmuth ; Bowler, D. R. ; Aebi, Philipp ; Renner, Christoph

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...

Université de Fribourg

Reversible control of the electronic density of states at the Fermi level of Ca₃Co₄O9+δ misfit-layered oxide single crystals through O⁺/H⁺ plasma exposure

Moser, D. ; Garnier, Michael G. ; Karvonen, L. ; Shkabko, A. ; Aebi, Philipp ; Weidenkaff, A.

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...