Field-Driven Mott Gap Collapse and Resistive Switch in Correlated Insulators

Abstract

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 coexistence of a stable Mott insulator and a metastable metal. Considering a slab subject to a linear potential drop we find, by means of 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.

Multiple crossovers and coherent states in a Mott-Peierls insulator

“…This means that the lowenergy B and AB contributions to the quasi-particle peak separate. This behavior is similar to the MIT reported in a correlated two orbital model 32 . Despite the lack of a mass divergence, the transition does share a similarity with the MIT in the single band case, namely, that as the DOS(ω = 0) becomes zero the Kondo effect can no longer be sustained and the impurities lose their respective Kondo screening clouds.…”

Electrically Induced Multiple Metal-Insulator Transitions in Oxide Nanodevices

“…Although Joule heating seems to properly explain the origin of this breakdown, we should not discard that the electric field might also destabilize the insulating phase and contribute to trigger the MIT. [30,31].…”

Tailoring Materials for Mottronics: Excess Oxygen Doping of a Prototypical Mott Insulator

“…Mott insulators as “failed metals” have metallic charge carrier densities at integer band‐filling, but exhibit insulating behavior due to strong on‐site Coulomb interactions of the valence electrons. Detuning the band‐filling, e.g., by applying an external electric field, can trigger the Mott transition (MT) into the correlated metal phase rendering all previously localized electrons mobile in the ON‐state . Besides the large ON/OFF ratio and fast switching speed in such devices, the high charge carrier concentration allows for further miniaturization beyond the current limits set by the extremely small number of carriers in nanoscale semiconductor devices …”

“…Recently, the realization of a Mott transistor involving only moderate electric gate fields was suggested. Dynamical mean field theory‐based simulations have demonstrated that materials in the Mott insulating phase, but already near the MT, are highly sensitive to external parameters such as strain and temperature, and also electric fields . To reach the operating point close to the transition into the correlated metal phase, the development of methods to tune a material's position in the electronic phase diagram is crucial.…”