[Zurück]

A. Pustogow, V. Dobrosavljevic, M. Dressel, S. Fratini:
"Rise and Fall of Landau's Quasiparticles While Approaching the Mott Transition";
Hauptvortrag: Magnetism Seminar at Charles University, Prague, Charles University, Prague, Czech Republic (eingeladen); 07.04.2021.

Landau suggested that the low-temperature properties of metals can be understood in terms of long-lived quasiparticles with all complex interactions included in Fermi-liquid parameters, such as the effective mass m*. Despite its wide applicability, electronic transport in bad or strange metals and unconventional superconductors is controversially discussed towards a possible collapse of the quasiparticle concept. Crucial information on this issue can be obtained by frequency-resolved probes that measure the complex optical conductivity.
Here we explore the electrodynamic response of correlated metals at half filling for varying correlation strength upon approaching a Mott insulator. We reveal persistent Fermi-liquid behavior with pronounced quadratic dependences of the optical scattering rate on temperature and frequency, along with a puzzling elastic contribution to relaxation. The strong increase of the resistivity beyond the Ioffe-Regel-Mott limit is accompanied by a `displaced Drude peak' in the optical conductivity. Our results, supported by a theoretical model for the optical response, demonstrate the emergence of a bad metal from resilient quasiparticles that are subject to dynamical localization and dissolve near the Mott transition.