Strongly correlated metal interfaces in the Gutzwiller approximation

TL;DR

This paper investigates how spatial inhomogeneity affects strongly correlated electron systems, using the Gutzwiller approximation to analyze various metal and insulator interfaces, revealing exponential decay behaviors linked to physical properties.

Contribution

It applies a self-consistent Gutzwiller method to characterize interface properties in correlated systems, highlighting decay lengths and their divergence near the Mott transition.

Findings

Decay lengths are bulk properties with physical significance.

Decay length diverges as the Mott transition is approached.

Exponential decay behaviors are observed at interfaces.

Abstract

We study the effect of spatial inhomogeneity on the physics of a strongly correlated electron system exhibiting a metallic phase and a Mott insulating phase, represented by the simple Hubbard model. In three dimensions, we consider various geometries, including vacuum-metal-vacuum, a junction between a weakly and a strongly correlated metal, and finally the double junctions metal-Mott insulator-metal and metal-strongly correlated metal- metal. We applied to these problems the self-consistent Gutzwiller technique recently developed in our group, whose approximate nature is compensated by an extreme flexibility,ability to treat very large systems, and physical transparency. The main general result is a clear characterization of the position dependent metallic quasiparticle spectral weight. Its behavior at interfaces reveals the ubiquitous presence of exponential decays and crossovers, with decay lengths of clear physical significance. The decay length of metallic strength in a weakly-strongly correlated metal interface is due to poor screening in the strongly correlated side. The decay length of metallic strength from a metal into a Mott insulator (or into vacuum) is due to tunneling. In both cases, the decay length is a bulk property, and diverges with a critical exponent ($\sim 1/2$ in the present approximation, mean field in character) as the (continuous, paramagnetic) Mott transition is approached.