Philipp Werner, University of Fribourg
Nonequilibrium DMFT description of photo-doped Mott insulators
Nonequilibrium simulations of interacting lattice models provide new perspectives on correlation effects and give access to metastable states of matter. Mott insulators are particularly interesting for nonequilibrium studies, since they exhibit complex phase diagrams upon doping, and because the Mott gap provides protection against fast thermalization after photo-excitations. In this talk, I discuss mechanisms which control the time evolution of photo-doped charge carriers in Mott systems and the properties of photo-induced metastable states.
Anna Tamai, University of Geneva
Temperature evolution of quasiparticles in Sr2RuO4: from a Fermi liquid to a bad metal state
Sr2RuO4 has emerged as a key-model system for correlated electrons. The normal state of Sr2RuO4 is exceptionally well characterized and is generally regarded as the cleanest Fermi-liquid system amongst all transition metal oxides. Using laser-based angle resolved photoemission spectroscopy (ARPES) we obtained precise measurements of the Fermi surface and found that the apparent strong angular dependence of the self-energy arises from a substantial orbital mixing induced by spin-orbit coupling. A comparison to single-site dynamical mean-field theory (DMFT) further supports the notion of dominantly local orbital self-energies. Like many other correlated electron systems, Sr2RuO4 turns into a bad metal at high temperature. In recent experiments, we investigated the fate of quasiparticles during this crossover. In contrast to common ARPES beliefs, our experiments show that quasiparticles do not disappear via a vanishing quasiparticle weight Z. To the contrary, we find that Z increases with increasing temperature. Quasiparticles eventually vanish not by losing weight but by dissolving via excessive broadening. These findings are in semi-quantitative agreement with DMFT calculations.