title: Non-Fermi-liquid behaviour in La4Ru6O19.
abstract: Understanding the complexities of electronic and magnetic ground states in solids is one of the main goals of solid-state physics. Transition-metal oxides have proved to be particularly fruitful in this regard, especially for those materials with the perovskite structure, where the special characteristics of transition-metal-oxygen orbital hybridization determine their properties. Ruthenates have recently emerged as an important family of perovskites because of the unexpected evolution from high-temperature ferromagnetism in SrRuO3 to low-temperature superconductivity in Sr2RuO4 (refs 1, 2). Here we show that a ruthenate in a different structural family, La4Ru6O19, displays a number of highly unusual properties, most notably non-Fermi-liquid behaviour. The properties of La4Ru6O19 have no analogy among the thousands of previously characterized transition-metal oxides. Instead, they resemble those of CeCu6-xAux-a widely studied f-electron-based heavy fermion intermetallic compound that is often considered as providing the best example of non-Fermi-liquid behaviour. In the ruthenate, non-Fermi-liquid behaviour appears to arise from just the right balance between the interactions of localized electronic states derived from Ru-Ru bonding and delocalized states derived from Ru-O hybridization.
authors.affiliation: Department of Chemistry and Princeton Materials Institute, Princeton University, Princeton, New Jersey 08540, USA.
authors.forename: P
authors.initials: P
authors.lastname: Khalifah
authors.forename: K D
authors.initials: KD
authors.lastname: Nelson
authors.forename: R
authors.initials: R
authors.lastname: Jin
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Mao
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: Q
authors.initials: Q
authors.lastname: Huang
authors.forename: X P
authors.initials: XP
authors.lastname: Gao
authors.forename: A P
authors.initials: AP
authors.lastname: Ramirez
authors.forename: R J
authors.initials: RJ
authors.lastname: Cava