Magnetic profile of a graphene wrapped ferromagnetic surface

Graphene has one of the highest electron mobilities at room temperature, making it ideal for next generation electronic devices. However, due to its small spin-orbit coupling it is not possible to manipulate spins directly in a pristine graphene monolayer. This may be overcome by proximity to a ferromagnet. Recent theoretical and experimental publications [1] indicate that on a Ni surface the graphene band structure is spin split. The authors used XMCD to measure the magnetic moment induced on the $\pi$- electrons in graphene due to the proximity effect with Ni, obtaining a value between 0.05-0.10 $\mu_B$ per C atom. We have produced a uniform graphene layer grown by a CVD process directly a Ni coated substrate (the catalyst). By varying key growth parameters (temperature & pressure) the interaction between graphene and the catalyst can be tuned to provide strong epitaxial alignment between graphene and Ni or a more weakly oriented rotated alignment. We will present results showing a magnetic enhancement at the ferromagnet - C interface extracted from recent polarized neutron reflectivity measurement on both epitaxial and rotated graphene wrapped ferromagnetic surfaces. [1] V. Karpan, et al., Phys. Rev. B 78, 195419 (2008), M. Weser,et al., Appl. Phys. Lett. 96, 012504 (2010)