Magnetic heterostructure of graphene with a submonolayer magnet on silicon

Graphene provides a wealth of advantageous functionalities but lags behind in spintronic applications due to lack of magnetism. A solution currently explored is proximity coupling of graphene with a 2D magnet. Recently, a class of submonolayer 2D magnets – superstructures of metal atoms on semiconductor surfaces – has been discovered. In these materials, magnetic metal atoms are not screened by anions; therefore, such 2D magnets can be employed in formation of magnetic heterostructures. Here, we report synthesis of a submonolayer 2D magnet – a superstructure of Gd on silicon – and its integration with graphene to induce spin-related phenomena. Magnetic properties of the 2D magnet and its heterostructure with graphene are rather similar with the exception that the heterostructure acquires significant magnetic coercivity. Proximity to the 2D magnet strongly affects the transport properties of graphene; in particular, the anomalous Hall effect emerges signifying spin-polarization of the carriers. Quantum oscillations are tracked across the magnetic transition; their evolution can be rationalized as an order of magnitude increase in the effective mass in the magnetic state. Being seamlessly integrated with the silicon technological platform, the heterostructure makes a prospective material for graphene spintronics.