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Temperature dependence of the threshold magnetic field for nucleation and domain wall propagation in an inhomogeneous structure with grain boundary

Phys. Rev. B 94, 054430

2016年8月30日(火)

Sasmita Mohakud, Sergio Andraus, Masamichi Nishino, Akimasa Sakuma, and Seiji Miyashita ( https://doi.org/10.1103/PhysRevB.94.054430 )

Abstract

In order to study the dependence of the coercive force of sintered magnets on temperature, nucleation and domain wall propagation at the grain boundary are studied as rate-determining processes of the magnetization reversal phenomena in magnets consisting of bulk hard magnetic grains contacting via grain boundaries of a soft magnetic material. These systems have been studied analytically for a continuum model at zero temperature [A. Sakuma et al., J. Magn. Magn. Mater. 84, 52 (1990)]. In the present study, the temperature dependence is studied by making use of the stochastic Landau-Lifshitz-Gilbert equation at finite temperatures. In particular, the threshold fields for nucleation and domain wall propagation are obtained as functions of ratios of magnetic interactions and anisotropies of the soft and hard magnets for various temperatures. It was found that the threshold field for domain wall propagation is robust against thermal fluctuations, while that for nucleation is fragile. The microscopic mechanisms of the observed temperature dependence are discussed.

その他特記事項

The authors would like to thank Professor Roy Chantrell for stimulating discussions and also Dr. Satoshi Hirosawa and Dr. Kazuhiro Hono for valuable information on magnets.
The present work was supported by Grants-in-Aid for Scientific Research C (No. 25400391 and No. 26400324) from MEXT of Japan, and the Elements Strategy Initiative Center for Magnetic Materials under the outsourcing project of MEXT. The numerical calculations were supported by the supercomputer center of the ISSP of the University of Tokyo. S. Mohakud would like to acknowledge DST, Govt. of India for INSPIRE faculty award and research funding.


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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)
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東工大元素戦略拠点 (東京工業大学)
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構造材料元素戦略研究拠点 (京都大学)
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