Rise and fall of Landau’s quasiparticles while approaching the Mott transition

• Published in: Nature communications Vol. 12; no. 1; pp. 1571 - 8
• Main Authors: Pustogow, Andrej, Saito, Yohei, Löhle, Anja, Sanz Alonso, Miriam, Kawamoto, Atsushi, Dobrosavljević, Vladimir, Dressel, Martin, Fratini, Simone
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.03.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/2795; 639/766/119/995; 639/766/119/999; 639/766/483/640; Charge transport; Condensed Matter; Correlation; Elastic scattering; Electrical resistivity; Electron transport; Elementary excitations; Humanities and Social Sciences; Localization; Low temperature; Metals; multidisciplinary; Physics; Science; Science (multidisciplinary); Strongly Correlated Electrons; Unconventional superconductors
• DOI: 10.1038/s41467-021-21741-z
• ISSN: 2041-1723

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. 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. Charge transport in strongly correlated electron systems is not fully understood. Here, the authors show that resilient quasiparticles at finite frequency persist into the bad-metal regime near a Mott insulator, where dynamical localization results in a ‘displaced Drude peak’ and strongly enhanced dc resistivity.