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arXiv 1602.03285cond-mat.mtrl-sci
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非均匀晶界结构中形核和畴壁扩展阈值磁场的温度依赖性

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

Sasmita Mohakud, Sergio Andraus, Masamichi Nishino, Akimasa Sakuma, Seiji Miyashita

摘要:

为了研究烧结磁体的矫顽力对温度的依赖性,研究了晶界处的形核和畴壁扩展作为磁体中磁化反转现象的速率决定过程,所述磁体由通过软磁材料的晶界接触的大块硬磁颗粒组成。这些系统已被研究分析为一个连续模型在零温度(A。Sakuma等人,J. Mag. Mag. Mat. { \bf 84} 52(1990))。在本研究中,温度依赖性研究利用随机Landau-Lifshitz-Gilbert方程在有限温度下。特别是,成核和畴壁传播的阈值场作为不同温度下的软,硬磁体的磁相互作用和各向异性的比率的函数。结果表明,畴壁扩展的阈值场对热涨落是鲁棒的,而形核的阈值场是脆弱的。所观察到的温度依赖性的微观机制进行了讨论。

英文摘要:

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. Mag. Mag. Mat. {\bf 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.

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