Vanadium dioxide (VO\(_2\)) is a material that undergoes an insulator–metal transition upon heating above 340 K. It remains debated as to whether this electronic transition is driven by a corresponding structural transition or by strong electron–electron correlations. Here, we use apertureless scattering near-field optical microscopy to compare nanoscale images of the transition in VO\(_2\) thin films acquired at both mid-infrared and terahertz frequencies, using a home-built terahertz ...
