Degradation of La0.8Ca0.2MnO3 single crystal surface: Electron spectroscopy studies

The electronic structure of degraded (as grown and chemically polished) and ion-sputtered La0.8Ca0.2MnO3 single crystal surfaces has been studied by X-ray photoemission and Auger electron spectroscopy techniques. XPS spectra of deep core levels (Mn2p, O1s, La3d, La4d) were taken from as grown, chemically polished and cleaned in UHV by Ar+ ion-bombardment surfaces. XPS data show different oxidation state of Mn and La ions on the degraded and ion-sputtered surfaces of the manganite crystal. Mn2p3/2 line width and energy position suggest mixed valence state of the manganese ions at the degraded and ion-sputtered crystal surfaces.