Angle Resolved Photoemission Study of Epitaxial Chromium Dioxide Films

Chromium dioxide is predicted to be a half-metallic oxide. The electronic properties of the surface region of CrO2 have been studied by performing angle-resolved ultra-violet photoelectron spectroscopy (ARUPS) measurements on epitaxial CrO2 films. The CrO2 thin films were deposited on (100) and (110) – oriented TiO2 substrates by chemical vapor deposition. Previous measurements of the transport properties of devices made from epitaxial CrO2 films have shown very little spin polarization. Possible sources of this low yield are a surface Cr2O3 phase and/or surface contamination. The effects of sputtering the CrO2 films to remove the outer layer of Cr2O3 and any surface contaminants and of annealing the films in oxygen to heal surface were examined. The ARUPS spectra of the CrO2 films have been compared to epitaxial Cr2O3 films prepared on Pt(111). In addition, low energy electron diffraction patterns of the sputtered and annealed CrO2 films have been prepared indicating that the surface remains in a CrO2 phase