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

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.