The intrinsic field effect, the change in surface conductance with an applied transverse electric field, of prototypal strongly correlated ${\mathrm{VO}}_2$ has remained elusive. Here we report its measurement enabled by epitaxial ${\mathrm{VO}}_2$ and atomic layer deposited high-$\kappa$ dielectrics. Oxygen migration, joule heating, and the linked field-induced phase transition are precluded. The field effect can be understood in terms of field-induced carriers with densities up to $\sim 5\times {10}^{13}{\mathrm{cm}}^{-2}$ which are strongly localized, as shown by their low, thermally activated mobility ($\sim 1\times {10}^{-3}{\mathrm{cm}}^2/\mathrm{V}\mathrm{s}$ at 300 K). These carriers show behavior consistent with that of Holstein polarons and strongly impact the (opto)electronics of ${\mathrm{VO}}_2$.

• Received 19 January 2015

DOI:https://doi.org/10.1103/PhysRevLett.115.196401