Depth-resolved XMCD study on single- and bi-layer graphene / Ni structure

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

The interaction of graphene with a metal is of both fundamental and technological interest in view of possible device applications. In the present study, depth-resolved X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) spectroscopy have been applied to the single layer graphene (SLG) grown on the Ni(111) substrate by ultrahigh vacuum chemical vapor deposition method to clear the electronic and spin states in the graphene/ferromagnetic metal interface. As a results, the intense XMCD signal derived from SLG is successfully detected, which indicates that the spin polarization in SLG is induced by Ni magnetization. And it is also found that the observed XMCD intensity is drastically changed depending on the probing depth. As for the Ni layer, the magnetization of the Ni atoms near the interface is decreased by 20-30% than that of Ni atoms far from the interface. This is considered that the magnetic structures of Ni atoms are changed by the formation of C-Ni bond.