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Matsumoto, Yoshihiro; Entani, Shiro; Otomo, Manabu; Avramov, P.; Naramoto, Hiroshi*; Amemiya, Kenta*; Sakai, Seiji
no journal, ,
In the present study, the electronic and magnetic states of the graphene/FM interface are investigated for the single-layer graphene (SLG)/Ni(111) and bilayer graphene (BLG)/Ni(111) structures by using the depth-resolved X-ray magnetic circular dichroism (XMCD) spectroscopy. For the SLG/Ni(111) structure, an intense XMCD signal was observed in the C K-edge XMCD spectrum measured by reversing the remanent magnetization of Ni(111). This indicates that spin polarization is induced in the 
-orbitals of SLG by the contact with Ni(111) even at room temperature. More interestingly, the BLG/Ni(111) structure is found to show the C K-edge XMCD signal whose intensity changes dramatically with the probing depth. On the other hand, the depth-resolved analysis of the Ni L-edge XMCD spectrum demonstrated that the magnetization of Ni decreases by 20-30 % within a few atomic layers from the graphene (SLG, BLG)/Ni(111) interfaces, possibly associated with the formation of C-Ni bonds.
Entani, Shiro; Matsumoto, Yoshihiro; Otomo, Manabu; Sakuraba, Yuya*; Avramov, P.; Naramoto, Hiroshi*; Takanashi, Koki; Sakai, Seiji
no journal, ,
Otomo, Manabu; Matsumoto, Yoshihiro; Entani, Shiro; Avramov, P.; Naramoto, Hiroshi*; Amemiya, Kenta*; Sakai, Seiji
no journal, ,
Graphene has been intensively studied in the last few years for its high carrier mobility and long spin coherent length. The performance of graphene spintronic devices, however, are strongly influenced by poor spin injection efficiency at graphene/ferromagnetic metal (FM) interface, mainly due to the conductance mismatch. A promising solution for improving spin injection efficiency is to insert a tunnel barrier between graphene and FM. It was reported that Al
O
and MgO which are conventionally used as a barrier material induce damage to graphene. In this study, we propose hexagonal boron nitride (h-BN) as a novel tunnel barrier for graphene spintronics based on the investigation of spintronic and electronic properties of the h-BN/Ni interface.
Sakai, Seiji; Matsumoto, Yoshihiro; Otomo, Manabu; Entani, Shiro; Avramov, P.; Naramoto, Hiroshi*; Fujikawa, Takashi*
no journal, ,