Integrating MBE materials with graphene to induce novel spin-based phenomena

TL;DR

This paper explores how molecular beam epitaxy (MBE) can modify graphene's surface to induce novel spin-dependent phenomena, including exchange splitting and defect-induced magnetic moments, advancing spintronics research.

Contribution

It presents experimental methods for integrating ferromagnetic insulators with graphene and investigates defect-induced magnetism using non-local spin transport.

Findings

Epitaxial growth of EuO on graphene demonstrated.

Defect-induced magnetic moments affect spin transport.

Exchange fields are highly gate-dependent, influencing g-factors.

Abstract

Magnetism in graphene is an emerging field that has received much theoretical attention. In particular, there have been exciting predictions for induced magnetism through proximity to a ferromagnetic insulator as well as through localized dopants and defects. Here, we discuss our experimental work using molecular beam epitaxy (MBE) to modify the surface of graphene and induce novel spin-dependent phenomena. First, we investigate the epitaxial growth the ferromagnetic insulator EuO on graphene and discuss possible scenarios for realizing exchange splitting and exchange fields by ferromagnetic insulators. Second, we investigate the properties of magnetic moments in graphene originating from localized p_z-orbital defects (i.e. adsorbed hydrogen atoms). The behavior of these magnetic moments is studied using non-local spin transport to directly probe the spin-degree of freedom of the defect-induced states. We also report the presence of enhanced electron g-factors caused by the exchange fields present in the system. Importantly, the exchange field is found to be highly gate dependent, with decreasing g-factors with increasing carrier densities.