Metal–insulator transition of VO2 thin films grown on TiO2 (001) and (110) substrates

Abstract

The effect of uniaxial stress along the c axis on the metal–insulator transition of ${\mathrm{VO}}_2$ has been studied in the form of epitaxial thin films grown on ${\mathrm{TiO}}_2$ (001) and (110) substrates. A large reduction in the transition temperature $T_{\mathrm{MI}}$ from 341 K for a single crystal to 300 K has been observed in the film on ${\mathrm{TiO}}_2$ (001) where the c-axis length is compressed owing to an epitaxial stress, while the $T_{\mathrm{MI}}$ has been increased to 369 K in the film on ${\mathrm{TiO}}_2$ (110) where the c-axis length is expanded. The correlation between the c-axis length and $T_{\mathrm{MI}}$ is suggested: the shorter c-axis length results in the lower $T_{\mathrm{MI}}.$