Modification Of Electronic Structure In Compressively Strained Vanadium Dioxide Films

Vanadium dioxide (VO2) undergoes a phase transition between an insulating monoclinic phase and a conducting rutile phase. Like other correlated electron systems, the properties of VO2 can be extremely sensitive to small changes in external parameters such as strain. In this paper, we investigate a compressively strained VO2 film grown on (001) quartz substrate in which the phase transition temperature (T-c) has been depressed to 325 K from the bulk value of 340 K. Infrared and optical spectroscopy reveals that the lattice dynamics of this strained film are similar to unstrained VO2. However, some of the electronic interband transitions of the strained VO2 film are significantly shifted in energy from those in unstrained VO2. The lattice dynamics remain largely unchanged while the T-c and some of the electronic interband transitions differ substantially from the bulk values, which highlights the role of electronic correlations in driving this metal-insulator phase transition.