Highly spin-polarized chromium dioxide thin films prepared by chemical vapor deposition from chromyl chloride

Highly spin-polarized chromium dioxide (CrO2) thin films were deposited on (100) TiO2 substrates by chemical vapor deposition using chromyl chloride as a precursor. The spin polarization, as measured by the point contact Andreev reflection technique, was 81±3%. X-ray diffraction θ/2θ scans indicated the films grew completely (100) oriented, in registry with the (100) oriented TiO2 substrate. X-ray diffraction φ scans on the CrO2 (110) reflection indicated the expected twofold symmetry, with no evidence of misaligned material. The resistivity at room temperature was 240 μΩ cm and decreased to 10 μΩ cm at 5 K, consistent with metallic behavior. The films were ferromagnetic with a Curie temperature of 395 K and a coercivity of ∼100 Oe at 298 K. The use of chromyl chloride as a precursor resulted in efficient and controlled CrO2 film growth.