[11p-Z08-1~19] 10.1 Emerging materials in spintronics and magnetics (including fabrication and charactrization methodologies)

▼ [11p-Z08-13] Characterization of ultrathin Co₂FeSi/MgO structure with scanning transmission electron microscope

〇(M2)Eisuke Matsushita¹, Yota Takamura¹, Shigeki Nakagawa¹ (1.Tokyo Tech)

Keywords:full-Heusler alloy, perpendicular magnetic anisotropy, scanning transmission electron microscope

We have been demonstrated that full-Heulser Co₂FeSi (CFS) alloy and MgO bilayers showed perpendicular magnetic anisotropy (PMA). Previously, the mechanism of PMA was evaluated. It suggested that the crystal structure of CFS was changed when CFS thickness wis 0.7 nm. In this paper, we investigated the origin of PMA with the crystallographic analysis using a scanning transmission electron microscope (STEM) in ultrathin CFS films. CFS was formed layered structure with certain roughness. Composition analysis implied interdiffusion of Si. The lattice constant was analyzed in CFS layer from the STEM images. The horizontal lattice constant did not show significant difference between the two samples with different thickness. In addition, in the 1.4 nm thick CFS samples, the horizontal and the vertical atomic distance were almost the same. The ultrathin CFS layers showed different crystallographic features from those of tens nm thick CFS.