Dynamics of a hole in a CuO4 plaquette: Electron energy-loss spectroscopy of Li2CuO2

Abstract

We have measured the energy- and momentum-dependent loss function of Li2CuO2 single crystals by means of electron energy-loss spectroscopy in transmission. Using the same values for the model parameters, the low-energy features of the spectrum as well as published Cu 2P3/2 x-ray photoemission data of Li2CuO2 are well described by a cluster model that consists of a single CuO4 plaquette only. This demonstrates that charge excitations in Li2CuO2 are strongly localized. © 2000 The American Physical Society.