Hubbard gap modulation in vanadium dioxide nanoscale tunnel junctions.

We locally investigate the electronic transport through individual tunnel junctions containing a 10 nm thin film of vanadium dioxide (VO2) across its thermally induced phase transition. The insulator-to-metal phase transition in the VO2 film collapses the Hubbard gap (experimentally determined to be 0.4 ± 0.07 V), leading to several orders of magnitude change in tunnel conductance. We quantitatively evaluate underlying transport mechanisms via theoretical quantum mechanical transport calculations which show excellent agreement with the experimental results.