Quantum Conductance Probing of Oxygen Vacancies in SrTiO3 Epitaxial Thin Film Using Graphene

TL;DR

This study uses quantum Hall conductance in graphene to non-invasively probe oxygen vacancies in SrTiO3 thin films, revealing their impact on dielectric properties through systematic conductance changes.

Contribution

It introduces a novel method employing graphene's quantum Hall conductance to analyze oxygen vacancies in SrTiO3 epitaxial films, linking dielectric behavior with vacancy dynamics.

Findings

Oxygen vacancies cause hysteretic conductance in graphene.

Linear scaling relation between capacitance and voltage sweep range.

Quantum Hall conductance effectively probes ionic phenomena in oxides.

Abstract

The quantum Hall conductance in monolayer graphene on an epitaxial SrTiO3 (STO) thin film is studied to understand the role of oxygen vacancies in determining the dielectric properties of STO. As the gate voltage sweep range is gradually increased in our device, we observe systematic generation and annihilation of oxygen vacancies evidenced from the hysteretic conductance behavior in graphene. Furthermore, based on the experimentally observed linear scaling relation between the effective capacitance and the voltage sweep range, a simple model is constructed to manifest the relationship among the dielectric properties of STO with oxygen vacancies. The inherent quantum Hall conductance in graphene can be considered as a sensitive, robust, and non-invasive probe for understanding the electronic and ionic phenomena in complex transition metal oxides without impairing the oxide layer underneath.