Magnetoresistance effects in multilayer graphene as grown on ferromagnetic substrates and implications for spin filtering

Multilayer graphene (MLG) or thin graphitic films as grown on nickel (Ni) or cobalt (Co) has been recently proposed as a promising platform for realizing highly efficient spin filters. However, graphene forms chemisorption interface with Ni and Co, which significantly affects the electronic properties of the interfacial layers as well as the growth of the subsequent graphene layers. Such systems can give rise to various types of magnetoresistance (MR) effects that are completely unrelated to spin filtering. It is, therefore, important to understand these MR effects in order to identify the spin filtering related signal. In this work we highlight on the various MR effects that are observed in Ni/MLG systems and that are also unrelated to spin filtering. In particular, an “interlayer magnetoresistance” (ILMR) effect manifests in these systems, which can result in large MR values that are comparable to state-of-the-art magnetic tunnel junctions at similar operating conditions. Preliminary measurements on Co/MLG samples also indicate presence of ILMR effect.