Calculating Macroscopic Resistance Of Vanadium Dioxide Thin Film During Metal Insulator Phase Transition

Vanadium Dioxide (VO2) exhibits unique pattern formation while it undergoes temperature-driven Metal-Insulator (MI) phase transition. We use optical microscopy techniques to take videos of the surface of thin film VO2, simultaneously measuring resistance. We observed patches of metal and insulator form while undergoing MI phase transition and showed hysteretic effects. To get the per-pixel resistance corresponding to a specific greyscale value, we feed the bulk resistance obtained from the experiment to a 2-D Random Field Ising Model. By converting each site of the RFIM into an insulating(-1) or a metallic(1) node into four resistors, we generated a 2D resistor grid. To reduce the resistor network into a single effective resistance, we developed an efficient Bond Propagation Algorithm mediated by Y-Delta/Delta-Y transformations in JAVA. Now that we have a correspondence between greyscale values and resistance, we use a similar approach on the images to convert each pixel into four resistors based on its greyscale value to get another 2D resistor network. By rerunning Bond Propagation Algorithm, we get a direct relationship between temperature and macroscopic resistance. We can confirm that these results are closely matched by plotting these results against the experiment. We can use this tool to perform computational analysis to further our understanding of temperature-driven phase transition in VO2 and open new avenues in nanoelectronics and neuromorphic computing.