Perfect dc conductance of a finite width Mott insulator sandwiched between metallic leads at zero temperature: a quantum emergent phenomenon in strongly correlated multilayers

TL;DR

This paper demonstrates that a finite-width Mott insulator between metallic leads exhibits perfect zero-temperature conductance due to a quantum emergent Fermi liquid state, but this ideal behavior is fragile under real-world conditions.

Contribution

The study reveals that inhomogeneous dynamical mean-field theory predicts perfect conductance in finite Mott barriers at zero temperature, highlighting a novel quantum emergent phenomenon in strongly correlated multilayers.

Findings

Finite Mott insulators between metals are Fermi liquids at T=0.

Perfect conductance is fragile to finite frequency, temperature, disorder, and magnetism.

Numerical studies show conditions for observing this phenomenon in experiments.

Abstract

Using inhomogeneous dynamical mean-field theory, we argue that the normal-metal proximity effect forces any finite number of "barrier" planes that are described by the (paramagnetic) Hubbard model and sandwiched between semi-infinite metallic leads to always be a Fermi liquid at T=0. This then implies that the inhomogeneous system restores lattice periodicity at zero frequency, has a well-defined Fermi surface, and should display perfect (ballistic) conductivity or "transparency". These results are, however, fragile with respect to finite frequency, V, T, disorder, or magnetism, all of which restore the expected quantum tunneling regime through a finite-width Mott insulator. Our formal results are complemented by numerical renormalization group studies on small thickness barriers that illustrate under what circumstances this behavior might be seen in real experimental systems.