title: Temperature Dependence of Magnetically Active Charge Excitations in Magnetite across the Verwey Transition.
abstract: We study the electronic structure of bulk single crystals and epitaxial films of Fe_{3}O_{4}. Fe 2p core level spectra show clear differences between hard x-ray (HAX) and soft x-ray photoemission spectroscopy (PES). The bulk-sensitive spectra exhibit temperature (T) dependence across the Verwey transition, which is missing in the surface-sensitive spectra. By using an extended impurity Anderson full-multiplet model-and in contrast to an earlier peak assignment-we show that the two distinct Fe species (A and B site) and the charge modulation at the B site are responsible for the newly found double peaks in the main peak above T_{V} and its T-dependent evolution. The Fe 2p HAXPES spectra show a clear magnetic circular dichroism (MCD) in the metallic phase of magnetized 100-nm-thick films. The model calculations also reproduce the MCD and identify the contributions from magnetically distinct A and B sites. Valence band HAXPES shows a finite density of states at E_{F} for the polaronic half metal with a remnant order above T_{V} and a clear gap formation below T_{V}. The results indicate that the Verwey transition is driven by changes in the strongly correlated and magnetically active B-site electronic states, consistent with resistivity and optical spectra.
authors.affiliation: Material Science, Nara Institute of Science and Technology (NAIST), Ikoma, Nara 630-0192, Japan.|RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Taguchi
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Chainani
authors.affiliation: National Institute for Materials Science (NIMS), SPring-8, Sayo, Hyogo 679-5148, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ueda
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Matsunami
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ishida
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Eguchi
authors.affiliation: National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0003, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Tsuda
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Takata
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yabashi
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tamasaku
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nishino
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Material Science, Nara Institute of Science and Technology (NAIST), Ikoma, Nara 630-0192, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Daimon
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Todo
authors.affiliation: ISIR-Sanken, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Oura
authors.affiliation: JASRI/SPring-8, Sayo, Sayo, Hyogo 679-5198, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Senba
authors.affiliation: JASRI/SPring-8, Sayo, Sayo, Hyogo 679-5198, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ohashi
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.|Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Shin