Magnetoelectronic Properties of Graphene - Antiferromagnetic Insulator Heterostructures*

Recently, graphene has been theorized to exhibit either ferromagnetism or antiferromagnetism induced by the magnetic proximity effect when placed on a proper magnetic substrate. In order to induce proximity magnetoelectronic effects, the substrate needs to satisfy three criteria. First, it should be insulating, so the graphene provides the only transport channel. Second, the orbitals of the antiferromagnet should hybridize with those of graphene sufficiently to induce sizable exchange and spin-orbit coupling fields. And finally, the substrate’s magnetization should be sufficiently weak so that magnetization measurements of the graphene are not obscured by the underlying magnetic layer. The antiferromagnetic (weak ferromagnet) insulator NiF₂ grown via the molecular beam epitaxy on MgF₂, is a suitable candidate due to its weak antiferromagnetic property. The Graphene-NiF₂ heterostructure was fabricated using a stamping technique in a glovebox to prevent interfacial contamination. The proximity coupling was studied with magnetotransport measurement and the electronic structure by measuring electronic spectroscopy using scanning tunneling microscopy at low temperatures. The results of these measurements will be discussed.