Strong interactions, or correlations, between the d or f electrons in transition-metal oxides lead to various types of metal-insulator transitions that can be triggered by external parameters such as temperature, pressure, doping, magnetic fields and electric fields. Electric-field-induced metallization of such materials from their insulating states could enable a new class of ultrafast electronic switches and latches. However, significant questions remain about the detailed nature of the switching process. Here, we show, in the canonical metal-to-insulator transition system V₂O₃, that ultrafast voltage pulses result in its metallization only after an incubation time that ranges from ∼150 ps to many nanoseconds, depending on the electric field strength. We show that these incubation times can be accounted for by purely thermal effects and that intrinsic electronic-switching mechanisms may only be revealed using larger electric fields at even shorter timescales.

Thin films of V2O3 were grown epitaxially on c-plane sapphire substrates by oxygen plasma-assisted thermal evaporation. Reducing the amount of oxygen supplied during growth led to a nearly 50 K increase in V2O3’s metal-insulator transition temperature to a temperature as high as 184 K. By systematically varying the oxygen pressure the transition temperature monotonically increased, which was accompanied by a concomitant increase in the room-temperature resistivity. These trends are consistent with a continuous change in the stoichiometry of V2O3.

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