A Metal-Insulator Transition of the Buried MnO2 Monolayer in Complex Oxide Heterostructure

TL;DR

This paper reports the discovery of a metal-insulator transition in a MnO2 monolayer embedded in complex oxide heterostructures, revealing new phenomena driven by dimensional confinement and boundary conditions.

Contribution

It demonstrates how electrostatic boundary conditions can tune the electronic and magnetic states of a 2D oxide monolayer within heterostructures, combining advanced characterization techniques.

Findings

Observation of a metal-insulator transition in MnO2 monolayer

Associated magnetic transition identified

Methodology for characterizing buried oxide monolayers

Abstract

Functionalities in crystalline materials are determined by 3-dimensional collective interactions of atoms. The confinement of dimensionality in condensed matter provides an exotic research direction to understand the interaction of atoms, thus can be used to tailor or create new functionalities in material systems. In this study, a 2-dimensional transition metal oxide monolayer is constructed inside complex oxide heterostructures based on the theoretical predictions. The electrostatic boundary conditions of oxide monolayer in the heterostructure is carefully designed to tune the chemical, electronic, and magnetic states of oxide monolayer. The challenge of characterizing such an oxide monolayer is overcome by a combination of transmission electron microscopy, x-ray absorption spectroscopy, cross-sectional scanning tunneling microscopy, and electrical transport measurements. An intriguing metal-insulator transition associated with a magnetic transition is discovered in the MnO2 monolayer. This study paves a new route to understand the confinement of dimensionality and explore new intriguing phenomena in condensed matters.