  The proposed switching mechanism is based on an electronically-induced
metal-insulator transition occurring in conditions of the excess
non-equilibrium carrier density under the applied electric field. First, this
mechanism is developed on the basis of a phenomenological approach. This model
not only allows the qualitative description of the switching mechanism, but it
is in quantitative agreement with the experimental results, in particular, with
those concerning the critical concentration and threshold field. The mechanism
takes into account the dependence of the carrier density on electric field, as
well as the scaling of the critical field. Next, we show that such a
'macroscopic' approach can be supported by some microscopic model. The
quintessence of this approach consists in the fact that an electronically
induced metal-insulator transition may be described in terms of
Bardeen-Cooper-Schrieffer (BCS) formalism developed earlier for the charge
density wave concept. It is shown that for the combination of both the types of
interaction (electron-electron and electron-phonon), the formation of a
collective excitation - an electron crystal of charge density wave - in the
model of exciton insulator is possible, which, in a general case, can also be
accompanied by a structural transition. The results for vanadium dioxide are
examined within the frameworks of the developed approach.
