Micromagnetic simulation on magnetic properties of Nd<sub>2</sub>Fe<sub>14</sub>B/α-Fe nanocomposites with Fe nanowires as the soft phase

doi:10.1007/s11706-018-0436-x

Front. Mater. Sci.

2018, Vol. 12

Issue (4) : 348-353 https://doi.org/10.1007/s11706-018-0436-x

RESEARCH ARTICLE

Micromagnetic simulation on magnetic properties of Nd₂Fe₁₄B/α-Fe nanocomposites with Fe nanowires as the soft phase

Wei LI, Lizhong ZHAO, Zhongwu LIU(

)

School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China

Download: PDF(338 KB) HTML
Export: BibTeX | EndNote | Reference Manager | ProCite | RefWorks

Abstract

Fe nanowire array with strong shape anisotropy was employed as the soft phase in Nd–Fe–B based nanocomposites. The effects of the Fe nanowire distribution on magnetic properties of the nanocomposites were investigated by micromagnetic simulation. The results indicate that the shape anisotropy of Fe wires added in the same direction as the uniaxial magnetocrystalline anisotropy of the hard phase cannot increase the coercivity of the nanocomposite. When the nanowires are distributed perpendicular to the easy axis of the hard phase, the shape anisotropy of soft phase can retard the moments from rotating to the full reversed direction, leading to enhanced coercivity. In addition, with increasing the nanowire diameter, the coercivity of the nanocomposite decreases, but the dipolar interaction shows different roles in magnetic reversal of nanocomposite for different distributions of nanowires. The current results suggest that the coercivity of the Nd₂Fe₁₄B/α-Fe nanocomposite can be enhanced by introducing the soft magnetic nanowire array with the diameter less than the exchange length and with the long axis along the direction other than the easy axis of hard phase.

Keywords Nd₂Fe₁₄B/α-Fe nanocomposite micromagnetic simulation Fe nanowires shape anisotropy exchange coupling

Corresponding Author(s): Zhongwu LIU

Online First Date: 18 September 2018 Issue Date: 10 December 2018

Cite this article:

Wei LI,Lizhong ZHAO,Zhongwu LIU. Micromagnetic simulation on magnetic properties of Nd₂Fe₁₄B/α-Fe nanocomposites with Fe nanowires as the soft phase[J]. Front. Mater. Sci., 2018, 12(4): 348-353.

URL:

https://academic.hep.com.cn/foms/EN/10.1007/s11706-018-0436-x
https://academic.hep.com.cn/foms/EN/Y2018/V12/I4/348

Fig.1 The simulation model.

Tab.1 Magnetic parameters used in the simulation [¹³]

Fig.2 The demagnetization curves along different directions for the Fe nanowire array with the nanowire diameter S = 9 nm.

Fig.3 The demagnetization curves of the nanocomposites with different θ angles.

Fig.4 The distribution of the magnetization in the demagnetization process in the section plane (x = 5 nm) parallel to the nanowire axis for θ = 0°, applied field H = −1440 kA/m (blue region is the reversed domain, and red region is the non-reversed domain).

Fig.5 The distribution of magnetization in the first step of reversal, corresponding to the reversible part of the demagnetization curve, for θ = 90°, applied field H = −1560 kA/m (a) in the section plane (x = 5 nm) parallel to the nanowire axis, and (b) in the section plane (z = 0) perpendicular to the nanowire axis.

Fig.6 The energy curves in the demagnetization process for θ = 0° and 90°.

Fig.7 The demagnetization curves of nanocompoistes with different nanowire diameters S for θ = 0° and 90°.

Fig.8 The distributions of the demagnetizing field (Z/Y component) of the hard phase in the saturated state in the section plane (x = 5 nm) parallel to the nanowire axis: (a) θ = 0°; (b) θ = 90° (positive values mean the field is along the non-reversed direction (+Z/+Y), negative values mean the field is along the reversed direction (−Z/−Y)).

1	Coehoorn R, de Mooij D B, de Waard C. Meltspun permanent magnet materials containing Fe3B as the main phase. Journal of Magnetism and Magnetic Materials, 1989, 80(1): 101–104 https://doi.org/10.1016/0304-8853(89)90333-8
2	Liu Z W, Zhao L Z. Compositional optimization and new processes for nanocrystalline NdFeB-based permanent magnets. In: Advances in Magnetic Materials: Processing, Properties, and Performance. CRC Press, 2017, 293–372
3	Zhang X Y, Wen G H, Chan Y F, et al.. Fabrication and magnetic properties of ultrathin Fe nanowire arrays. Applied Physics Letters, 2003, 83(16): 3341–3343 https://doi.org/10.1063/1.1621459
4	Yang S, Zhu H, Yu D, et al.. Preparation and magnetic property of Fe nanowire array. Journal of Magnetism and Magnetic Materials, 2000, 222(1–2): 97–100 https://doi.org/10.1016/S0304-8853(00)00541-2
5	Li W, Zhou Q, Zhao L Z, et al.. Micromagnetic simulation of anisotropic grain boundary diffusion for sintered Nd–Fe–B magnets. Journal of Magnetism and Magnetic Materials, 2018, 451: 704–709 https://doi.org/10.1016/j.jmmm.2017.12.002
6	Li W, Zhao L Z, Zhou Q, et al.. Effects of grain boundary configuration and characteristics on the demagnetization process and coercivity of anisotropic NdFeB magnets. Computational Materials Science, 2018, 148: 38–45 https://doi.org/10.1016/j.commatsci.2018.02.034
7	Fukunaga H, Ikeda M, Inuzuka A. A new type of nanocomposite magnets including elongated soft magnetic grains — computer simulation. Journal of Magnetism and Magnetic Materials, 2007, 310(2): 2581–2583 https://doi.org/10.1016/j.jmmm.2006.10.1082
8	Aharoni A. Introduction to the Theory of Ferromagnetism. Clarendon Press, 2000
9	The Object Oriented MicroMagnetic Framework (OOMMF). Available on line: (accessed April, 15, 2018)
10	Kneller E F, Hawig R. The exchange-spring magnet: a new material principle for permanent magnets. IEEE Transactions on Magnetics, 1991, 27(4): 3588 https://doi.org/10.1109/20.102931
11	Skomski R, Hadjipanayis G C, Sellmyer D J. Effective demagnetizing factors of complicated particle mixtures. IEEE Transactions on Magnetics, 2007, 43(6): 2956–2958 https://doi.org/10.1109/TMAG.2007.893798
12	Hubert A, Schäfer R. Magnetic Domains: The Analysis of Magnetic Microstructures. Springer Science & Business Media, 2008
13	Schrefl T, Fidler J. Micromagnetic simulation of magnetizability of nanocomposite Nd–Fe–B magnets. Journal of Applied Physics, 1998, 83(11): 6262–6264 https://doi.org/10.1063/1.367666
14	Porter D G, Donahue M J. Generalization of a two-dimensional micromagnetic model to non-uniform thickness. Journal of Applied Physics, 2001, 89(11): 7257–7259 https://doi.org/10.1063/1.1363606
15	Baik J M, Schierhorn M, Moskovits M. Fe nanowires in nanoporous alumina: Geometric effect versus influence of pore walls. The Journal of Physical Chemistry C, 2008, 112(7): 2252–2255 https://doi.org/10.1021/jp711621v
16	Lu B, Huang M Q, Chen Q, et al.. Magnetic coupling in boron-rich NeFeB nanocomposites. Journal of Applied Physics, 1999, 85(8): 5920–5922 https://doi.org/10.1063/1.369914

[1]	Wei LI, Lizhong ZHAO, Zhongwu LIU. Micromagnetic investigation by a simplified approach on the demagnetization field of permanent magnets with nonmagnetic phase inside[J]. Front. Mater. Sci., 2019, 13(3): 323-333.

Viewed

Full text

Abstract

Cited

Shared

Discussed