Probing the insulator-to-metal transition in VO₂ using non-contact atomic force microscopy

Vanadium dioxide (VO₂) undergoes an insulator-to-metal transition (IMT) when heated above a critical temperature of 340 K. The role of Joule heating and applied electric field in inducing this transition is an active area of research. In this study, the IMT of VO₂ thin films grown using oxygen plasma molecular beam epitaxy are examined using non-contact atomic force microscopy (AFM) in ultrahigh vacuum. By measuring the dissipated power through a qPlus AFM tuning fork, the competing effects of Joule heating and applied electric field are assessed. With this non-invasive and highly sensitive technique, we can measure the IMT as a function of tip-sample distance and bias voltage.