Mott insulators are "unsuccessful metals" in which Coulomb repulsion prevents charge conduction despite a metal-like concentration of conduction electrons. The possibility to unlock the frozen carriers with an electric field offers tantalizing prospects of realizing new Mott-based microelectronic devices. Here we unveil how such unlocking happens in a simple model that shows the coexistence of a stable Mott insulator and a metastable metal. Considering a slab subject to a linear potential drop, we find, by means of the dynamical mean-field theory, that the electric breakdown of the Mott insulator occurs via a first-order insulator-to-metal transition characterized by an abrupt gap collapse in sharp contrast to the standard Zener breakdown. The switch on of conduction is due to the field-driven stabilization of the metastable metallic phase. Outside the region of insulator-metal coexistence, the electric breakdown occurs through a more conventional quantum tunneling across the Hubbard bands tilted by the field. Our findings rationalize recent experimental observations and may offer a guideline for future technological research.
|Titolo:||Field-Driven Mott Gap Collapse and Resistive Switch in Correlated Insulators|
|Autori:||Mazza, G; Amaricci, A; Capone, M; Fabrizio, M|
|Rivista:||PHYSICAL REVIEW LETTERS|
|Data di pubblicazione:||2016|
|Digital Object Identifier (DOI):||10.1103/PhysRevLett.117.176401|
|Appare nelle tipologie:||1.1 Journal article|