  The metal insulator transition (MIT) in VO2 has been an important topic for
recent years. It has been generally agreed that the mechanism of the MIT in
bulk VO2 is considered to be a collaborative Mott-Peierls transition, however
the effect of the strain on the phase transition is much more complicated. In
this study the effect of the large strain on the properties of VO2 films was
investigated. One remarkable result is that highly strained epitaxial VO2 thin
films were rutile in the insulating state as well as in the metallic state.
These highly strained VO2 films underwent an electronic phase transition
without the concomitant Peierls transition. Our results also show that a very
large tensile strain along the c-axis of rutile VO2 resulted in a phase
transition temperature of ~ 433 K, much higher than in any previous report. Our
findings elicit that the metal insulator transition in VO2 can be driven by an
electronic transition alone, rather the typical coupled electronic-structural
transition.
