Anisotropic Metal-Insulator Transition in Epitaxial Thin Films

TL;DR

This paper investigates the anisotropic metal-insulator transition in epitaxial thin films of polyvalent metals, revealing directional coherence properties likely driven by Coulomb interactions and 2D Kondo screening.

Contribution

It introduces the concept of anisotropic metal-insulator transition in doped 2D Mott-Hubbard insulators and links it to Coulomb interactions and Kondo screening effects.

Findings

Coherent wave-like excitations normal to the film surface

Incoherent in-plane electronic behavior

Anisotropic coherence development related to Coulomb interactions

Abstract

Quantum wells made of simple polyvalent metals represent a novel family of doped 2D Mott-Hubbard insulators. As scanning tunneling microscopy experiments show, these systems exhibit an anisotropic form of metal-insulator transition. Their elementary excitations possess coherent wave-like properties along the normal axis, and show an incoherent behavior in-plane. The development of such an anisotropic coherence is most likely related to Coulomb interaction between localized and delocalized thin film electronic states - 2D Kondo screening.