Nanoparticle Induced Anomalous Hall Effect in Graphene.

Schemes for introducing magnetic properties into graphene are of fundamental interest and could enable the development of electrically controlled magnetic devices, thereby extending graphene's applications from conventional electronics to spintronics. Proximity-induced ferromagnetism (PIFM) has been reported for graphene coupled to adjacent ferromagnetic insulators (FMIs). PIFM from an FMI preserves graphene's high carrier mobility and does not introduce a parallel current path. However, few FMIs other than yttrium-iron-garnet are suitable for practical applications due to difficulties in their growth and deposition and to their typically low Curie temperatures. Furthermore, it is difficult to obtain a high-quality FMI/graphene interface by graphene transfer methods, which are essential for obtaining the required interfacial exchange coupling. Here, we report the observation of the anomalous Hall effect (AHE) in graphene proximity coupled to an array of magnetic nanoparticles. This observation of AHE in graphene in proximity to a discontinuous magnetic structure opens the door to realizing magnetic properties in graphene from a greatly expanded range of materials and offers new possibilities for realizing patterned spintronic devices and circuitry.