Metal–insulator-transition (MIT) of VO2has attracted
strong attention as a potential phenomenon to be utilized in nanostructured
devices. Dynamics of MIT phase transition determines the feasibility
of VO2material properties in various applications, for
example, photonic components, sensors, MEMS actuators, and neuromorphic
computing. However, conventional interface strain model predicts the
MIT effect accurately for bulk, but fairly for the thin films, and
thus, a new model is needed. It was found that the VO2thin
film–substrate interface plays a crucial role in determining
transition dynamics properties. In VO2thin films on different
substrates, coexistence of insulator-state polymorph phases, dislocations,
and a few unit cell reconstruction layer form an interface structure
minimizing strain energy by the increase of structural complexity.
As a consequence, MIT temperature and hysteresis of structure increased
as the transition enthalpy of the interface increased. Thus, the process
does not obey the conventional Clausius–Clapeyron law anymore.
A new model is proposed for residual strain energy potentials by implementing
a modified Cauchy strain. Experimental results confirm that the MIT
effect in constrained VO2thin films is induced through
the Peierls mechanism. The developed model provides tools for strain
engineering in the atomic scale for crystal potential distortion effects
in nanotechnology, such as topological quantum devices.