Significance of the inter-site Coulomb interaction between the O 2p and Cu 3d holes revealed by resonant inelastic x-ray scattering of Sr14Cu24O41

Abstract

We have carried out resonant inelastic x-ray scattering (RIXS) measurements at the Cu K-edge on Sr14Cu24O41, which has two kinds of layers, namely, the ladder layer and the chain layer. The excitation from the Zhang–Rice singlet band to the upper Hubbard band (UHB) shows a large dispersion with a periodicity of the ladder layer. The excitation corresponding to the ligand-to-metal charge transfer is nearly dispersionless. Comparison between the RIXS data and theoretical calculations shows that the inter-site Coulomb interaction between the Cu 3d and O 2p holes plays a prominent role in the RIXS process. This interaction is expected to be important in the hole state in the ladder layer of this compound.