Université de Fribourg

Rotation symmetry breaking in ${\mathrm{La}}_{2-x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ revealed by angle-resolved photoemission spectroscopy

Razzoli, Ellias ; Matt, Christian E. ; Sassa, Y. ; Månsson, M. ; Tjernberg, O. ; Drachuck, G. ; Monomo, M. ; Oda, M. ; Kurosawa, T. ; Huang, Y. ; Plumb, N. C. ; Radovic, M. ; Keren, Amit ; Patthey, Luc ; Mesot, Joël ; Shi, Ming

In: Physical Review B, 2017, vol. 95, no. 22, p. 224504

Using angle-resolved photoemission spectroscopy it is revealed that in the vicinity of optimal doping the electronic structure of La2−xSrxCuO4 cuprate undergoes an electronic reconstruction associated with a wave vector qa=(π,0). The reconstructed Fermi surface and folded band are distinct to the shadow bands observed in BSCCO cuprates and in underdoped La2−xSrxCuO4 with x≤0.12, which...

Université de Fribourg

Local terahertz field enhancement for time-resolved x-ray diffraction

Kozina, M. ; Pancaldi, Matteo ; Bernhard, Christian ; Driel, T. van ; Glownia, J. M. ; Maršík, Premysl ; Radovic, M. ; Vaz, Carlos A. F. ; Zhu, D. ; Bonetti, Stephano ; Staub, U. ; Hoffmann, Matthias C.

In: Applied Physics Letters, 2017, vol. 110, no. 8, p. 081106

We report local field strength enhancement of single-cycle terahertz (THz) pulses in an ultrafast time-resolved x-ray diffraction experiment. We show that patterning the sample with gold microstructures increases the THz field without changing the THz pulse shape or drastically affecting the quality of the x-ray diffraction pattern. We find a five-fold increase in THz-induced x-ray...

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...