film within the metal-insulator-transition*

Vanadium sesquioxide (V₂O₃) is an archetypal Mott insulator, and exhibits a first-order transition at 160 K between a low temperature monoclinic, antiferromagnetic insulator and a high temperature, rhombohedral, paramagnetic, metallic phase. Resistive noise as measured through electronic transport can be used as a probe of the fluctuating dynamics of the two-phase domain structure. We measure noise spectra at both low frequencies (up to 300 kHz) and radio frequencies (between 200 MHz and 1 GHz). At low current densities the noise power is quadratic in bias current, as expected for resistive fluctuations probed nonperturbatively by the current. The low frequency noise generally resembles flicker-type 1/f^a noise, often taking on the form of Lorentzian noise dominated by a small number of fluctuators as the insulating phase is approached. The presence of radio frequency noise power that is quadratic in the bias current allow identification of domain fluctuations with lifetimes below 1 ns, comparable to timescales seen in non-equilibrium pump-probe studies of the transition.