Integration of the Ferromagnetic Insulator EuO onto Graphene

TL;DR

This paper reports the successful growth of high-quality EuO ferromagnetic insulator films on graphene, enabling potential spintronic applications through exchange proximity interaction, with observed ferromagnetism and minimal impact on graphene's mobility.

Contribution

First demonstration of epitaxial EuO films on graphene, advancing the integration of ferromagnetic insulators for spintronic device development.

Findings

EuO films grown on graphene are crystalline and oriented (001).

EuO exhibits ferromagnetism with a Curie temperature of 69 K.

Minimal decrease in graphene mobility after EuO deposition.

Abstract

We have demonstrated the deposition of EuO films on graphene by reactive molecular beam epitaxy in a special adsorption-controlled and oxygen-limited regime, which is a critical advance toward the realization of the exchange proximity interaction (EPI). It has been predicted that when the ferromagnetic insulator (FMI) EuO is brought into contact with graphene, an overlap of electronic wavefunctions at the FMI/graphene interface can induce a large spin splitting inside the graphene. Experimental realization of this effect could lead to new routes for spin manipulation, which is a necessary requirement for a functional spin transistor. Furthermore, EPI could lead to novel spintronic behavior such as controllable magnetoresistance, gate tunable exchange bias, and quantized anomalous Hall effect. However, experimentally, EuO has not yet been integrated onto graphene. Here we report the successful growth of high quality crystalline EuO on highly-oriented pyrolytic graphite (HOPG) and single-layer graphene. The epitaxial EuO layers have (001) orientation and do not induce an observable D peak (defect) in the Raman spectra. Magneto-optic measurements indicate ferromagnetism with Curie temperature of 69 K, which is the value for bulk EuO. Transport measurements on exfoliated graphene before and after EuO deposition indicate only a slight decrease in mobility.