Dynamic Modulation of Phase Transition by External Strain Engineering in Quasi-van der Waals Epitaxial VO₂ Films on Fluorophlogopite

Unique metal–insulator transition behaviors of strongly correlated electronic materials, vanadium dioxide (VO₂), and their wide potential applications have gained much attention for investigation. In this research, high-quality epitaxial films of VO₂ (020) are directly grown on fluorophlogopite (001) substrates, and the relationship between phase-transition temperature and external strains is revealed. After verifying the like-freestanding property and low intrinsic resistance changing of VO₂/fluorophlogopite, variable phase-transition temperatures under different external strains with a tuning rate of 5.37 K per 0.1% strain are obtained. Based on experimental results and theoretical calculation, it is speculated that lattice constant and bandgap between d_// and π * are strongly affected by the external strains, which allow for more effective dynamic modulation of phase-transition process. This research provides a comprehensive understanding of strain engineering on phase-transition properties and also broadens the possibility of potential applications of certain optoelectronic devices for strain modulation.