Point defects on graphene on metals

TL;DR

This study investigates how single carbon vacancies in graphene on a Pt(111) substrate influence its electronic, structural, and magnetic properties, revealing increased reactivity and altered magnetic moments due to substrate coupling.

Contribution

It provides new insights into how metallic substrates affect defect-induced properties in graphene, combining experimental STM data with density functional theory analysis.

Findings

Vacancies create broad electronic resonances above the Fermi level.

Vacancy sites become more reactive and enhance graphene-metal coupling.

Magnetic moments associated with vacancies are quenched by substrate interactions.

Abstract

Understanding the coupling of graphene with its local environment is critical to be able to integrate it in tomorrow's electronic devices. Here we show how the presence of a metallic substrate affects the properties of an atomically tailored graphene layer. We have deliberately introduced single carbon vacancies on a graphene monolayer grown on a Pt(111) surface and investigated its impact in the electronic, structural and magnetic properties of the graphene layer. Our low temperature scanning tunneling microscopy studies, complemented by density functional theory, show the existence of a broad electronic resonance above the Fermi energy associated with the vacancies. Vacancy sites become reactive leading to an increase of the coupling between the graphene layer and the metal substrate at these points; this gives rise to a rapid decay of the localized state and the quenching of the magnetic moment associated with carbon vacancies in free-standing graphene layers.