title: Detection of Zhang-Rice singlets using spin-polarized photoemission.
abstract: From a spin-resolved photoemission study on the Bi(2)Sr(2)CaCu(2)O(8+delta) superconductor, we show experimentally that the first ionization state is of nearly pure singlet character. This is true both above and below the superconducting transition and in the presence of doping and band formation. This provides direct support for the existence and stability of Zhang-Rice singlets in high-temperature superconductors, justifying the ansatz of single-band models. Moreover, we establish this technique as an important probe for a wide range of cuprates and strongly correlated materials.
authors.affiliation: European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble, France.
authors.forename: N B
authors.initials: NB
authors.lastname: Brookes
authors.forename: G
authors.initials: G
authors.lastname: Ghiringhelli
authors.forename: O
authors.initials: O
authors.lastname: Tjernberg
authors.forename: L H
authors.initials: LH
authors.lastname: Tjeng
authors.forename: T
authors.initials: T
authors.lastname: Mizokawa
authors.forename: T W
authors.initials: TW
authors.lastname: Li
authors.forename: A A
authors.initials: AA
authors.lastname: Menovsky