Interface induced room-temperature ferromagnetism in hydrogenated epitaxial graphene

TL;DR

This study demonstrates room-temperature ferromagnetism in hydrogenated epitaxial graphene on SiC, driven by electron correlation effects involving the buffer layer, despite the non-magnetic nature of the constituents.

Contribution

It reveals a novel ferromagnetic phenomenon in hydrogenated epitaxial graphene induced by interface interactions, not explained by magnetic impurities.

Findings

Strong ferromagnetism observed at room temperature.

Ferromagnetism linked to electron correlation effects in buffer layer.

Curie temperature exceeds 300 K.

Abstract

Due to the predominantly surface character of graphene, it is highly suitable for functionalization with external atoms and/or molecules leading to a plethora of new and interesting phenomena. Here we show ferromagnetic properties of hydrogen-functionalized epitaxial graphene on SiC. Ferromagnetism in such a material is not directly evident as it is inherently composed of only non-magnetic constituents. Our results nevertheless show strong ferromagnetism, which cannot be explained by simple magnetic impurities. The ferromagnetism is unique to hydrogenated epitaxial graphene on SiC, where interactions with the interfacial buffer layer play a crucial role. We argue that the origin of the observed ferromagnetism is governed by electron correlation effects of the narrow Si-dangling-bond (Si-DB) states in the buffer layer exchange-coupled to localized states in the hydrogenated graphene layer. This forms a quasi-three-dimensional ferromagnet with a Curie temperature higher than 300 K.