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

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Physics

Background:

• Mott insulators are materials that resist electrical conduction due to strong electron-electron interactions (Coulomb repulsion).
• These materials possess a high concentration of electrons but behave as insulators, hence termed 'unsuccessful metals'.
• The potential to induce conductivity with an electric field presents opportunities for novel Mott-based microelectronic devices.

Purpose of the Study:

• To elucidate the mechanism of electric field-induced conduction in Mott insulators.
• To investigate the coexistence of stable Mott insulating and metastable metallic phases.
• To understand the nature of the insulator-to-metal transition under an applied electric field.

Main Methods:

• Utilized the dynamical mean-field theory (DMFT) to model a Mott insulator slab.
• Applied a linear potential drop across the slab to simulate electric field effects.
• Analyzed the electronic band structure and phase transitions.

Main Results:

• Discovered that electric breakdown in certain Mott insulators occurs via a first-order insulator-to-metal transition.
• Observed an abrupt collapse of the Mott gap, distinct from Zener breakdown.
• Identified field-driven stabilization of a metastable metallic phase as the key mechanism for conduction onset.
• Showcased conventional quantum tunneling across tilted Hubbard bands in regions without phase coexistence.

Conclusions:

• Electric fields can induce a sharp insulator-to-metal transition in Mott insulators by stabilizing a metallic phase.
• The findings provide a theoretical framework for understanding electric breakdown in these materials.
• This research offers valuable insights for the design and development of future Mott-based electronic devices.