Manipulation of film quality and magnetic properties of CrO2 (100) films on TiO2 substrates with carrier gas and growth temperature
Abstract
High-quality CrO2 films were synthesized on TiO2 (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 CrO2 films can be reduced to 310 or 300 °C when using Ar or N2 as the carrier gas, respectively. The quality of CrO2 film on TiO2 substrate can thus be improved by optimizing growth temperature in a much larger range (310–400 °C in Ar and 300–430 °C in N2, in contrast with 390–410 °C in O2), which is significant for the practical application of CrO2 films. The best film quality was achieved at 320 °C in either Ar or N2 atmosphere, at which CrO2 film has its narrowest orientation distribution and lowest roughness. Compared to films grown in O2, films grown in Ar were found to have larger saturation magnetizations (Ms) and magnetic anisotropies, possibly due to numerous O vacancies. Films grown in N2 are actually N-doped films, and have lower Ms than those grown in O2. The Curie temperature (Tc) was also tuned by the carrier gas and growth temperature. Films grown in Ar or N2 generally have a higher Tc value than those grown in O2. Furthermore, the thermal stability of the films was found to be remarkably improved when using N2 as the carrier gas.