Electric-field-driven Mott metal-insulator transition in correlated thin films: An inhomogeneous dynamical mean-field theory approach

Abstract

Simulations are carried out based on the dynamical mean-field theory (DMFT) in order to investigate the properties of correlated thin films for various values of the chemical potential, temperature, interaction strength, and applied transverse electric field. Application of a sufficiently strong field to a thin film at half-filling leads to the appearance of conducting regions near the surfaces of the film, whereas in doped slabs the application of a field leads to a conductivity enhancement on one side of the film and a gradual transition to the insulating state on the opposite side. In addition to the inhomogeneous DMFT, an independent layer approximation (ILA) is considered, in which the properties of each layer are approximated by a homogeneous bulk environment. A comparison between the two approaches reveals that the less expensive ILA results are in good agreement with the DMFT approach, except close to the metal-to-insulator transition points and in the layers immediately at the film surfaces. The hysteretic behavior (memory effect) characteristic of the bulk doping driven Mott transition persists in the slab.

Metal-Mott insulator interfaces

“…To render the equations soluble in the transition region, we compute the lattice Green's function and use its local component G n1n1 to map the system to a chain of N auxiliary impurity problems [18],…”

“…As a first step towards characterizing the metal-Mott interface, we compute the real-space structure of the interfaces for the canonical example of a correlated system, the single-band Hubbard model. We use techniques in the spirit of work on correlated surfaces [12,13] and heterostructures [14][15][16][17][18]. We extract the evolution of the density, double-occupancy and spectral features across the interface, allowing us to determine the parameters of the underlying free energy across the phase diagram.…”

Charge redistribution in correlated heterostuctures within nonequilibrium real-space dynamical mean-field theory

“…[18][19][20] Due to the local Hubbard and long-range Coulomb interaction present in these systems, charge redistribution takes place. [20][21][22] The equilibrium situation was addressed, e.g., in Refs. 21 and 22.…”

Interfaces in coexisting metals and Mott insulators

“…To render the equations soluble in the transition region, we compute the lattice Green's function and use its local component G n1n1 to map the system to a chain of N auxiliary impurity problems 12 ,…”

“…Extensive work has also examined Mott systems in inhomogeneous geometries, exploring correlated surfaces and heterostructures, where the Coulomb repulsion or hopping is varied spatially [10][11][12] . Enhanced correlations are found at vacuumfacing surfaces of Mott insulators due to reduced coordination and consequent decrease in kinetic energy 13,14 .…”