title: Resonant inelastic x-ray scattering study of charge excitations in La(2)CuO(4).
abstract: We report a resonant inelastic x-ray scattering study of the dispersion relations of charge-transfer excitations in insulating La(2)CuO(4).. These data reveal two peaks, both of which show two-dimensional characteristics. The lowest energy excitation has a gap energy of approximately 2.2 eV at the zone enter, and a dispersion of approximately 1 eV. The spectral weight of this mode becomes dramatically smaller around (pi, pi). The second peak shows a smaller dispersion ( approximately 0.5 eV) with a zone-center energy of approximately 3.9 eV. We argue that these are both highly dispersive exciton modes damped by the presence of the electron-hole continuum.
authors.affiliation: Department of Physics, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Kim
authors.forename: J P
authors.initials: JP
authors.lastname: Hill
authors.forename: C A
authors.initials: CA
authors.lastname: Burns
authors.forename: S
authors.initials: S
authors.lastname: Wakimoto
authors.forename: R J
authors.initials: RJ
authors.lastname: Birgeneau
authors.forename: D
authors.initials: D
authors.lastname: Casa
authors.forename: T
authors.initials: T
authors.lastname: Gog
authors.forename: C T
authors.initials: CT
authors.lastname: Venkataraman