Rise and Fall of Landau's Quasiparticles While Approaching the Mott Transition

Understand

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 $m^{\star}$.

• 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.
• 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.