title: Optical response of Sr2RuO4 reveals universal fermi-liquid scaling and quasiparticles beyond Landau theory.
abstract: We report optical measurements demonstrating that the low-energy relaxation rate (1/τ) of the conduction electrons in Sr(2)RuO(4) obeys scaling relations for its frequency (ω) and temperature (T) dependence in accordance with Fermi-liquid theory. In the thermal relaxation regime, 1/τ ∝ (ħω)(2)+(pπk(B)T)(2) with p = 2, and ω/T scaling applies. Many-body electronic structure calculations using dynamical mean-field theory confirm the low-energy Fermi-liquid scaling and provide quantitative understanding of the deviations from Fermi-liquid behavior at higher energy and temperature. The excess optical spectral weight in this regime provides evidence for strongly dispersing "resilient" quasiparticle excitations above the Fermi energy.
authors.affiliation: Département de Physique de la Matière Condensée, Université de Genève, 24 quai Ernest-Ansermet, 1211 Genève 4, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Stricker
authors.affiliation: Jožef Stefan Institute, Jamova 39, Ljubljana 1000, Slovenia.
authors.forename: J
authors.initials: J
authors.lastname: Mravlje
authors.affiliation: Département de Physique de la Matière Condensée, Université de Genève, 24 quai Ernest-Ansermet, 1211 Genève 4, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Berthod
authors.affiliation: CNR-SPIN, and Dipartimento di Fisica "E. R. Caianiello", Universita di Salerno, I-84084 Fisciano (Salerno) Italy.
authors.forename: R
authors.initials: R
authors.lastname: Fittipaldi
authors.affiliation: CNR-SPIN, and Dipartimento di Fisica "E. R. Caianiello", Universita di Salerno, I-84084 Fisciano (Salerno) Italy.
authors.forename: A
authors.initials: A
authors.lastname: Vecchione
authors.affiliation: Département de Physique de la Matière Condensée, Université de Genève, 24 quai Ernest-Ansermet, 1211 Genève 4, Switzerland and Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France and Centre de Physique Théorique, École Polytechnique, CNRS, 91128 Palaiseau, France.
authors.forename: A
authors.initials: A
authors.lastname: Georges
authors.affiliation: Département de Physique de la Matière Condensée, Université de Genève, 24 quai Ernest-Ansermet, 1211 Genève 4, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: van der Marel