Electrical field induced shift of the Mott Metal-Insulator transition in thin films

TL;DR

This study explores how an external electric field influences the Mott metal-insulator transition in thin films, revealing that the field shifts the transition and causes surface metallicity to persist longer than in the bulk.

Contribution

It demonstrates how an electric field can modulate the Mott transition in thin films, showing surface metallicity can be maintained while the bulk becomes insulating, a novel insight into electric field effects on correlated materials.

Findings

Electric field shifts the Mott transition to higher Hubbard U values.

Surface layers remain metallic under electric field even when the bulk is insulating.

Electric field screening occurs only at higher Hubbard U values.

Abstract

The ground state properties of a paramagnetic Mott insulator are investigated in the presence of an external electrical field using the inhomogeneous Gutzwiller approximation for a single band Hubbard model in a slab geometry. The metal insulator transition is shifted towards higher Hubbard repulsions by applying an electric field perpendicular to the slab. The spatial distribution of site dependent quasiparticle weight shows that the quasiparticle weight is maximum in few layers beneath the surface. Moreover only at higher Hubbard repulsion, larger than the bulk critical U, the electric field will be totally screened only for centeral cites. Our results show that by presence of an electric field perpendicular to a thin film made of a strongly correlated material, states near the surface will remain metallic while the bulk becomes insulating after some critical U. In contrast, in the absence of the electric field the surface becomes insulating before the bulk.