Tuning the metal insulator transition (MIT) behavior of VO2 film through the interfacial strain is effective for practical applications. However, the mechanism for strain-modulated MIT is still under debate. Here we directly record the strain dynamics of ultrathin VO2 film on TiO2 substrate and reveal the intrinsic modulation process by means of synchrotron radiation and first-principles calculations. It is observed that the MIT process of the obtained VO2 films can be modulated continuously via the interfacial strain. The relationship between the phase transition temperature and the strain evolution is established from the initial film growth. From the interfacial strain dynamics and theoretical calculations, we claim that the electronic orbital occupancy is strongly affected by the interfacial strain, which changes also the electron-electron correlation and controls the phase transition temperature. These findings open the possibility of an active tuning of phase transition for the thin VO2 film through the interfacial lattice engineering.

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Vanadium pentoxide (V2O5) films capped with a thin ZnO layer were prepared by magnetron sputtering at room temperature. The effect of annealing on the microstructure and optical properties of films was systematically investigated. Results indicated that the initially smooth films transformed to porous composite nanocrystals at 500 °C and then further to agglomerated nanoslices at 550 °C. This microstructure transformation is attributed to the distinct temperature-sensitive crystallization of V2O5. The annealed films exhibited enhanced visible photoluminescence, which was attributed to the coupling between V2O5 nanorods and ZnO nanoparticles as well as the improved V2O5 crystallinity.