Manipulation of film quality and magnetic properties of CrO 2 (100) films on TiO 2 substrates with carrier gas and growth temperature.

High-quality CrO 2 films were synthesized on TiO 2 (100) substrates at different temperatures using the chemical vapor deposition method in argon or nitrogen atmosphere. It was found that the lower limit for the growth temperature of CrO 2 films can be reduced to 310 or 300 °C when using Ar or N 2 as the carrier gas, respectively. The quality of CrO 2 film on TiO 2 substrate can thus be improved by optimizing growth temperature in a much larger range (310-400 °C in Ar and 300-430 °C in N 2 , in contrast with 390-410 °C in O 2 ), which is significant for the practical application of CrO 2 films. The best film quality was achieved at 320 °C in either Ar or N 2 atmosphere, at which CrO 2 film has its narrowest orientation distribution and lowest roughness. Compared to films grown in O 2 , films grown in Ar were found to have larger saturation magnetizations ( M s ) and magnetic anisotropies, possibly due to numerous O vacancies. Films grown in N 2 are actually N-doped films, and have lower M s than those grown in O 2 . The Curie temperature ( T c ) was also tuned by the carrier gas and growth temperature. Films grown in Ar or N 2 generally have a higher T c value than those grown in O 2 . Furthermore, the thermal stability of the films was found to be remarkably improved when using N 2 as the carrier gas.