[18p-PB1-1~84] 10 Spintronics and Magnetics (Poster)

[18p-PB1-8] Graphene on the L1₀-ordered alloy epitaxial films

〇Hiroshi Naganuma^2,3,1, C.-W. Wu⁶, J.-C. Hu⁶, G. Florian⁴, A. Snader⁴, C. Carretero⁴, R. Nicolas⁴, B. Dlubak⁴, P. Seneor^4,5 (1.CIES Tohoku Univ., 2.CSRN Tohoku Univ., 3.CSIS Tohoku Univ., 4.CNRS/Thales, 5.Univ. Paris-sud, 6.MA-tec)

Keywords:Graphene, FePd, L10-ordered alloy

L1₀-ordered alloys are attracted much attention for use in HDD and MRAM because of their high uniaxial magnetocrystalline anisotropy and low damping constant (α_eff ~0.007). However, L1₀-ordered alloy has a large lattice misfit (~10%) to the MgO barrier. Graphene (Gr) can be formed without concern of the epitaxial relationship. Therefore, magnetic tunnel junctions (p-MTJs) using L1₀-ordered alloy films and Gr are useful in highly integrated MRAM systems. In this study, crystal structure and interfacial properties were investigated for Gr on atomically flat L1₀-FePd epitaxial films. L1₀-FePd films were grown on the SrTiO₃ (100) substrates by highly vacuumed r.f. magnetron sputtering. After removing the surface oxide layer by chemical etching, Gr was deposited by chemical vapor deposition method. The surface roughness of the FePd films by atomic force microscopy was Ra of less than 0.4 nm. The structure of the L1₀-FePd films were evaluated by out-of-plane X-ray diffraction and cross-sectional scanning transmission electron microscopy (STEM). The L1₀-FePd was epitaxially grown on the SrTiO₃ substrate and a local contrast less than 5 nm in diameter was observed by STEM image. Kerr measurements showed that the remanence magnetization (M_r/M_s) at zero magnetic field was 0.2 and it was approximately 1.0 when a magnetic field of ~100 Oe was applied. It may consider that the magnetic domains of FePd aligned anitiferromagnetically without magnetic field due to small domains. The interface between FePd and Gr was confirmed by glance angle X-ray photoelectron spectroscopy (XPS), and no chemical reaction and oxidation could be observed; the Gr was successfully grown on the L1₀-FePd epitaxial films.