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Interlayer Exchange Coupling Constant in Nd-Fe-B/Ni80Fe20 Films by All-Optical Pump-Probe Technique

マグネティックス研究会

2018年3月10日(土)

MANDALRuma(NIMS)、Ogawa Daisuke(NIMS)、Tamazawa Yukiya(Tohoku Gakuin University)、Ishioka Kunie(NIMS)、Shima Toshiyuki(Tohoku Gakuin University)、Kato Takeshi(Nagoya University)、Iwata Satosh(Nagoya University)、Takahashi Yukiko(NIMS)、Hirosawa Satoshi(NIMS)、Hono Kazuhiro(NIMS)

Abstract

We estimated the interlayer exchange coupling (Jex) between hard magnetic Nd-Fe-B and soft magnetic Ni80Fe20 layers by means of all-optical time-resolved magneto-optical Kerr effect (TRMOKE). Single Nd-Fe-B layer showed very high coercivity (μ0Hc) of 2T and resonance frequency (fr) is 169 GHz at external bias magnetic field (μ0Hb) 2 T, which was due to the high anisotropy field. By the deposition of Ni80Fe20 layer on the Nd-Fe-B layer, μ0Hc and fr reduced to 1.34 T and 74.4 GHz, respectively. Mo insertion between hard and soft magnetic layers made the recovery of μ0Hc to 1.9 T and further decrement of the fr to 63.7 GHz, which was close to that of Ni80Fe20. By fitting the magnetic field dependence of fr to a simple macro-spin model, it was found that Jex reduced from 4 mJ/m2 to 0 mJ/m2 by the insertion of 1 nm-thick Mo. Therefore, the recovery of μ0Hc and the reduction of fr were attributed to the decoupling of the interlayer exchange coupling between Nd-Fe-B and Ni80Fe20 layers. Although it was difficult to obtain the uniform spin precession in the high anisotropic and μ0Hc system, we had successfully established the estimation method of the interlayer exchange coupling constant in the hard/soft magnetic bilayer system, which would be applicable to the estimation of the intergranular exchange coupling.


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元素戦略プロジェクト(活動紹介)

元素戦略拠点

触媒・電池元素戦略拠点
触媒・電池元素戦略研究拠点 (京都大学)
東工大元素戦略拠点
東工大元素戦略拠点 (東京工業大学)
構造材料元素戦略研究拠点
構造材料元素戦略研究拠点 (京都大学)
高効率モーター用磁性材料技術研究組合
高効率モーター用 磁性材料技術研究組合