title: High-energy anomaly in the band dispersion of the ruthenate superconductor.
abstract: We reveal a "high-energy anomaly" (HEA) in the band dispersion of the unconventional ruthenate superconductor Sr2RuO4, by means of high-resolution angle-resolved photoemission spectroscopy (ARPES) with tunable energy and polarization of incident photons. This observation provides another class of correlated materials exhibiting this anomaly beyond high-T(c) cuprates. We demonstrate that two distinct types of band renormalization associated with and without the HEA occur as a natural consequence of the energetics in the bandwidth and the energy scale of the HEA. Our results are well reproduced by a simple analytical form of the self-energy based on the Fermi-liquid theory, indicating that the HEA exists at a characteristic energy scale of the multielectron excitations. We propose that the HEA universally emerges if the systems have such a characteristic energy scale inside of the bandwidth.
authors.affiliation: Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-0046, Japan. h-iwasawa@hiroshima-u.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Iwasawa
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshida
authors.forename: I
authors.initials: I
authors.lastname: Hase
authors.forename: K
authors.initials: K
authors.lastname: Shimada
authors.forename: H
authors.initials: H
authors.lastname: Namatame
authors.forename: M
authors.initials: M
authors.lastname: Taniguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Aiura