title: Orbital-Dependent Band Narrowing Revealed in an Extremely Correlated Hund's Metal Emerging on the Topmost Layer of Sr_{2}RuO_{4}.
abstract: We use a surface-selective angle-resolved photoemission spectroscopy and unveil the electronic nature on the topmost layer of Sr_{2}RuO_{4} crystal, consisting of slightly rotated RuO_{6} octahedrons. The γ band derived from the 4d_{xy} orbital is found to be about three times narrower than that for the bulk. This strongly contrasts with a subtle variation seen in the α and β bands derived from the one-dimensional 4d_{xz/yz}. This anomaly is reproduced by the dynamical mean-field theory calculations, introducing not only the on-site Hubbard interaction but also the significant Hund's coupling. We detect a coherence-to-incoherence crossover theoretically predicted for Hund's metals, which has been recognized only recently. The crossover temperature in the surface is about half that of the bulk, indicating that the naturally generated monolayer of reconstructed Sr_{2}RuO_{4} is extremely correlated and well isolated from the underlying crystal.
authors.affiliation: ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kondo
authors.affiliation: Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan.|RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ochi
authors.affiliation: ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nakayama
authors.affiliation: Department of Materials Science and Engineering, Iwate University, Morioka 020-8551, Japan.|Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Taniguchi
authors.affiliation: ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Akebi
authors.affiliation: ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kuroda
authors.affiliation: Hiroshima Synchrotron Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Arita
authors.affiliation: RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Sakai
authors.affiliation: Hiroshima Synchrotron Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Namatame
authors.affiliation: Hiroshima Synchrotron Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan.|Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Maeno
authors.affiliation: RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Arita
authors.affiliation: ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Shin