Detecting nanoscale size dependence in VO2 phase transition using a split-ring resonator metamaterial.

We have measured the size dependence of a solid-solid phase transformation in discrete nanoscale volumes of vanadium dioxide (VO(2)) defined by split-ring resonators. By monitoring the in-coupling plasmonic mode while thermally cycling through the insulator-metal transition, we show that hysteresis width broadens with reduced interrogation volume (i.e., number of intrinsic nucleation sites). The results further imply a volume range over which both electronic and structural components of the switching exhibit similar size dependence.