透過電子顕微鏡によるCo/Pd人工格子膜の格子歪解析

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We investigated the lattice strain in epitaxially grown [001]-oriented Co/Pd superlattices on MgO (001) single-crystal substrates, using high-resolution transmission electron microscopy. We observed the elastic deformation of the lattice arrangement from cubic to tetragonal, due to lateral coherency strain, and an intermixed Co-Pd layer with a thickness of 0.5 nm. The tetragonal deformation in the Co-Pd intermixed layer caused by stretching strain from the Pd layer induces high negative magneto-elastic energy via positive magnetostriction, resulting in a high negative contribution to perpendicular magnetic anisotropy energy. In a Co layer less than 0.5 nm thick, the perpendicular anisotropy is enhanced by the relaxation of the lattice strain resulting from the selection of a sinusoidal composition distribution in the modulated direction. We found that post-deposition annealing of [001]-oriented Co/Pd superlattices can improve the perpendicular magnetic anisotropy through the effect of interfacial mixing, which can relax the coherency strain.
2003-04-01