Oxygen K-edge electron-energy-loss spectra have been measured for La1−xSrxMnO3 (0 ≤ x ≤ 0.7) and La0.7Sr0.3MnOz thin films as a function of x and z. The spectra show a prepeak at the Fermi level, corresponding to transitions to empty states in the O2p band, at the threshold of the K edge around 529 eV. This prepeak systematically increases with an increase in conductivity through divalent doping (x) or oxygen content (z). This confirms that these materials are charge-transfer-type oxides with carriers having significant oxygen 2p hole character. We argue that, the double exchange mechanism has to include the role of oxygen hole density to satisfactorily describe their transport properties.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)