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Temperature-dependent magnetization reversal process and coercivity mechanism in Nd-Fe-B hot-deformed magnets

Journal of Applied Physics

2015年12月21日(月)

118, 223903 (2015); ( doi: 10.1063/1.4937274 )
Satoshi Okamoto, Ryota Goto, Nobuaki Kikuchi, Osamu Kitakami, Takahiro Akiya, Hossein Sepehri-Amin, Tadakatsu Ohkubo, Kazuhiro Hono, Keiko Hioki, Atsushi Hattori

Abstract

Low coercivity and its large temperature dependence of a Nd2Fe14B magnet with respect to its magnetic anisotropy field have been addressed as the coercivity problem. To elucidate the physical origin of this problem, we have investigated the temperature dependence of the magnetization reversal behavior in the Nd-Fe-B hot-deformed magnet. Based on the analysis of the energy barrier evaluated from magnetic viscosity measurements, the coercivity problem is discussed in terms of the following three aspects: magnetization reversal process, intrinsic coercivity without thermal demagnetization effect, and energy barrier height. The analyses lead us to conclude that domain wall pinning is dominant in the magnetization reversal in the Nd-Fe-B hot-deformed magnet. The temperature dependences of the intrinsic coercivity and the energy barrier height are explained by the grain boundary model with an intermediate layer. These analyses would be utilized to discuss the detailed structure and magnetic properties of the grain boundary, which gives a new insight to overcome the coercivity problem.

その他特記事項

ESICMM,文科省「ナノマクロ物質・デバイス・システム創製アライアンス」,科研費 No. 424360261.


研究活動

元素戦略拠点

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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)
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高効率モーター用 磁性材料技術研究組合