Defect Driven Dynamics of the VO₂Metal-Insulator Transition

Metal-to-insulator transition (MIT) materials have been widely explored from fundamental perspectives. Among these, vanadium dioxide (VO₂) is a prime example, because of its close to ambient transition temperature (340 K). Besides many other technologically important applications, VO₂ is receiving increased attention as a basis material for energy efficient resistive switching-based devices. While the general aspects of the structural phase transition, optical properties and, filamentary MIT are well characterized, understanding the roles of Joule heating and pure electronic mechanism in the MIT is still controversial. In this work, we report on the temporal and spatial scales that impact the MIT. To ensure a controlled comparison in subsequent investigations, we obtain almost identical MIT by growing VO₂ thin films under the same conditions on different substrates. Our methodology provides access to fundamental quantities, including power consumption and timescales, which we find to be intimately related to nano-scale defects and microstructure.  We show that assumptions about homogeneity or microstructure are imperative to understand the resistive switching mechanism of quantum materials.