Quantum Sensing of Insulator-to-Metal Transitions in a Mott Insulator*

We studied the resistive switching properties of pristine and ion-irradiated VO2 thin film devices by performing optically detected diamond Nitrogen Vacancy (NV) electron spin resonance measurements. This switching behavior is of interest in the field of neuromorphic computing, in its potential application as an artificial neuron. Our measurements probe the local temperature and magnetic field in electrically biased VO2 devices, which agree global transport measurement results. In pristine devices, the electrically-driven IMT proceeds through Joule heating up to the transition temperature while in ion-irradiated devices, the transition occurs non-thermally, well below the transition temperature. This provides the first direct evidence for non-thermal electrically induced IMT in a Mott insulator, highlighting the significant opportunities offered by NV quantum sensors in exploring nanoscale thermal and electrical behaviors in Mott materials.