中国物理B ›› 2001, Vol. 10 ›› Issue (9): 862-868.doi: 10.1088/1009-1963/10/9/318

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ANISOTROPIC CHARACTERISTICS OF DEMAGNETIZATION CURVE FOR NANOCRYSTALLINE Nd-Fe-B MAGNET CALCULATED BY MICROMAGNETICS

金汉民, 王学凤, 赵素芬, 闫羽   

  1. Department of Physics, Jilin University, Changchun 130023, China
  • 收稿日期:2000-12-16 修回日期:2001-02-13 出版日期:2001-09-15 发布日期:2005-06-12
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 59871019).

ANISOTROPIC CHARACTERISTICS OF DEMAGNETIZATION CURVE FOR NANOCRYSTALLINE Nd-Fe-B MAGNET CALCULATED BY MICROMAGNETICS

Jin Han-min (金汉民), Wang Xue-feng (王学凤), Zhao Su-fen (赵素芬), Yan Yu (闫羽)   

  1. Department of Physics, Jilin University, Changchun 130023, China
  • Received:2000-12-16 Revised:2001-02-13 Online:2001-09-15 Published:2005-06-12
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 59871019).

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摘要： The demagnetization curves for nanocrystalline Nd-Fe-B magnets of a stoichiometric composition were calculated by making use of the finite element technique of micromagnetics. The curve, especially iHc, varies in a wide range with the direction of applied field if the grain number N is taken to be small. With the increase of N, the range becomes smaller and the average of iHc decreases and approaches a limit iHc(N=∞). iHc for finite N is larger than, or at least equal to, iHc(N=∞). Jr/Js is weakly affected by N and the field direction. Jr/Js(N=∞) decreases with the increase of grain size L. These are larger than the experimental values for the Nd-rich Nd2.33Fe14B1.06Si0.21 magnets by ～0.05. iHc(N=∞) increases with the increase of L, and is close to or somewhat smaller than the experimental values of the Nd-rich magnet, as would be expected. In contrast, the curve calculated for the non-interacting grain system (Stoner-Wohlfarth model) of N≥30 depends neither on the field direction nor on N.

Abstract: The demagnetization curves for nanocrystalline Nd-Fe-B magnets of a stoichiometric composition were calculated by making use of the finite element technique of micromagnetics. The curve, especially iHc, varies in a wide range with the direction of applied field if the grain number N is taken to be small. With the increase of N, the range becomes smaller and the average of iHc decreases and approaches a limit iHc(N = ∞). iHc for finite N is larger than, or at least equal to, iHc(N = ∞). Jr/Js is weakly affected by N and the field direction. Jr/Js(N = ∞) decreases with the increase of grain size L. These are larger than the experimental values for the Nd-rich Nd2.33Fe14B1.06Si0.21 magnets by ～0.05. iHc(N = ∞) increases with the increase of L, and is close to or somewhat smaller than the experimental values of the Nd-rich magnet, as would be expected. In contrast, the curve calculated for the non-interacting grain system (Stoner-Wohlfarth model) of N ≥ 30 depends neither on the field direction nor on N.

Key words: rare-earth Fe compound, high coercive force materials, magnetization curves, hysteresis loop, micromagnetism

中图分类号:  (Magnetization curves, hysteresis, Barkhausen and related effects)

  • 75.60.Ej
02.70.Dh (Finite-element and Galerkin methods) 75.50.Tt (Fine-particle systems; nanocrystalline materials) 75.30.Gw (Magnetic anisotropy)