ホーム > 研究活動 > 2020年 > Magnetic field threshold for nucleation and depinning of domain walls in the neodymium permanent magnet Nd2Fe14B

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Magnetic field threshold for nucleation and depinning of domain walls in the neodymium permanent magnet Nd2Fe14B

PHYSICAL REVIEW B 101, 094421 (2020)

2020年3月17日(火)

Ismail Enes Uysal、Masamichi Nishino、and Seiji Miyashita

Abstract

The Nd2 magnet Nd2Fe14B is an indispensable permanent magnet for high-technology commercial products. We study magnetization reversal in hard-soft-hard magnet systems of the atomistic model of the Nd magnet at zero and room temperatures. We present the nucleation and pinning fields as a function of the strength of the anisotropy energy of the soft magnet, estimated by using the stochastic Landau-Lifshitz-Gilbert equation. In the Nd magnet, reflecting the lattice structure, the properties of domain walls (DWs) depend on their moving directions. Bloch and Néel DWs move along the a (or b)and c axes, respectively. We investigate the difference in the nucleation and pinning fields between the Bloch and Néel DWs. We also analyze the dependence of the threshold fields on the thickness of the soft magnet. We find that the thermal fluctuation effect affects the threshold fields in the Nd magnet model more significantly than those in the simple anisotropic Heisenberg model [Mohakud et al., Phys. Rev. B 94, 054430 (2016)]. We also find that the strength of the anisotropy energies of the soft magnet phase is not so important for the pinning field, while it is essential for the nucleation fi eld, etc. We discuss the detailed features of the dependencies and their microscopic mechanisms.




研究活動

文部科学省

文部科学省
元素戦略プロジェクト(活動紹介)
NIMS磁石パートナーシップ

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