  Mott insulators can be portrayed as "unsuccessful metals": systems in which a
strong Coulomb repulsion prevents charge conduction notwithstanding the
metal-like density of conduction electrons. The possibility to unlock such
large density of frozen carriers with an electric field offers a tantalizing
opportunity to realize new Mott-based microelectronic devices. Here we
explicitly unveil how such unlocking happens by solving a simple, yet generic,
model for correlated insulators using dynamical mean-field theory.
Specifically, we show that the electric breakdown of a Mott insulator can occur
via a first-order insulator-to-metal transition, characterized by an abrupt
gap-collapse in sharp contrast to the Zener tunneling mechanism. The switch-on
of charge conduction is due to the energetic stabilization of a metallic phase
that preexists as metastable state in equilibrium and is disconnected from the
stable insulator. Our findings rationalize recent experimental observations and
offer a guideline for future technological research.
