Issue
EPL
Volume 79, Number 4, August 2007
Article Number 47012
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/79/47012
Published online 26 July 2007
EPL, 79 (2007) 47012
DOI: 10.1209/0295-5075/79/47012

Observation of multiple Zhang-Rice excitations in a correlated solid: Resonant inelastic X-ray scattering study of Li2CuO2

T. Learmonth1, C. McGuinness2, P.-A. Glans1, J. E. Downes3, T. Schmitt4, L.-C. Duda4, J.-H. Guo5, F. C. Chou6 and K. E. Smith1

1  Department of Physics, Boston University - 590 Commonwealth Ave., Boston, MA 02215, USA
2  School of Physics, Trinity College Dublin - Dublin 2, Ireland
3  Physics Department, Macquarie University - NSW 2109, Australia
4  Department of Physics, Uppsala University - Box 530, S-75121, Uppsala, Sweden
5  Advanced Light Source, Lawrence Berkeley National Laboratory - Berkeley, CA 94720, USA
6  Center for Materials Science and Engineering, Massachusetts Institute of Technology - Cambridge, MA 02139, USA

ksmith@bu.edu

received 19 January 2007; accepted in final form 2 July 2007; published August 2007
published online 26 July 2007

Abstract
Multiple Zhang-Rice type spectral features have been observed in resonant inelastic X-ray scattering (RIXS) from the quasi-one-dimensional cuprate charge transfer insulator Li2CuO2. The first feature appears at constant emission energy, and is associated with a Zhang-Rice singlet final state. The second is an interplaquette charge transfer excitation that results in a novel triplet Zhang-Rice-type final state. It is accompanied by the presence of a O 2p nonbonding to upper Hubbard band excitation at an energy close to that of a calculated triplet charge transfer Zhang-Rice-type excitation. The site selectivity and polarization rules associated with RIXS allows these two excitations to be distinguished.

PACS
74.72.-h - Cuprate superconductors (high-Tc and insulating parent compounds).
71.10.Li - Excited states and pairing interactions in model systems.
71.20.-b - Electron density of states and band structure of crystalline solids.

© Europhysics Letters Association 2007