title: Angle-resolved photoemission study of the MX-chain compound [Ni(chxn)(2)Br]Br(2): spin-charge separation in hybridized d-p chains.
abstract: We report on the results of angle-resolved photoemission experiments on a quasi-one-dimensional (1D) MX-chain compound [Ni(chxn)2Br]Br2, which shows a gigantic nonlinear optical effect. A "band" having about 500 meV energy dispersion is found in the first half of the Brillouin zone, but disappears at kb/pi approximately 1/2. These spectral features are well reproduced by the d-p chain model with a small charge-transfer energy Delta compared with that of 1D Cu-O compounds. We propose that this smaller Delta is the origin of the absence of clear spin-charge separation in the photoemission spectra and the strong nonlinear optical effect.
authors.affiliation: Synchrotron Radiation Research Center, Japan Atomic Energy Research Institute, SPring-8, Mikazuki, Hyogo 679-5148, Japan.
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Fujimori
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ino
authors.forename: Testuo
authors.initials: T
authors.lastname: Okane
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fujimori
authors.forename: Kozo
authors.initials: K
authors.lastname: Okada
authors.forename: Toshio
authors.initials: T
authors.lastname: Manabe
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamashita
authors.forename: Hideo
authors.initials: H
authors.lastname: Kishida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Okamoto