Bulk and surface physical properties of a CrO₂ thin film prepared from a Cr₈ O₂₁ precursor

We have prepared a CrO₂ thin film by chemical vapor deposition from a Cr₈ O₂₁ precursor and studied the bulk and surface physical properties. The CrO₂ thin film is grown on a TiO₂ (100) substrate by heating of a Cr₈ O₂₁ precursor and TiO₂ (100) substrate together in a sealed quartz tube. The prepared film is found from x-ray diffraction analysis to be an (100)-oriented single phase. The magnetization and resistivity measurements indicate that the film is a ferromagnetic metal with a Curie temperature of about 400 K. Cr 3s core-level and valence band photoelectron spectroscopy spectra reveal the presence of a metallic CrO₂ in the surface region of the film. Our work indicates that preparation from a Cr₈ O₂₁ precursor is promising for obtaining a CrO₂ thin film with the metallic surface.