Depth-resolved XMCD spectroscopy on single-layer graphene / Ni structure

Matsumoto, Yoshihiro; Entani, Shiro; Otomo, Manabu; Avramov, P.; Naramoto, Hiroshi*; Amemiya, Kenta*; Sakai, Seiji

The graphene-metal interaction is not only of fundamental interest but also of technological importance in view of spintronic applications. For the purpose of clarifying the electronic and magnetic states of graphene / ferromagnetic metal structure, depth-resolved X-ray absorption and X-ray magnetic circular dichroism (XMCD) spectroscopy are performed on the single- and bi-layer graphene /Ni(111) structures. An intense XMCD signal is observed in the C K-edge XMCD spectrum taken under the surface sensitive condition. This indicates that there exists the Ni-induced spin polarization in the -orbitals of graphene even at room temperature. The depth-resolved analysis of the Ni L-edge XMCD spectrum makes clear that the magnetization of Ni is decreased by 20-30% within a few atomic layers from the interface with single-layer graphen, possibly associated with the formation of C-Ni bonds.