Observation of the insulator to metal transition in VO₂ by non-contact AFM

VO₂ undergoes an insulator to metal transition (IMT) with a conductivity increase up to 5 orders of magnitude upon heating through 340 K. The interplay between Joule heating and electric field effects on inducing the IMT is an active area of research. Here we present non-contact atomic force microscopy (nc-AFM) measurements from a VO₂ film grown with oxygen plasma-assisted MBE. In nc-AFM, an oscillating qPlus sensor can locally and non-invasively detect the force and power dissipation between the tip and sample. As we ramp the voltage applied to the sample, we observe a rise and subsequent drop in the power dissipated, indicating the film has switched to the metallic state. We match the pre-transition power dissipated to Joule dissipation, highlighting the crucial role local heating plays in triggering the IMT in VO₂.