Magnetization reversal of exchange-coupled and exchange-decoupled Nd-Fe-B magnets observed by magneto-optical Kerr effect microscopy
Source abstract
Abstract
Abstract We observed the magnetization reversals of exchange-coupled and exchange-decoupled Nd-Fe-B sintered magnets with coercivities of 1.16 and 1.80 T, respectively, by magneto-optical Kerr effect (MOKE) microscopy. The cascade propagation of reversed magnetic domain throughout multiple grains was observed in the standard sintered magnet, in which Nd 2 Fe 14 B grains are believed to be exchange-coupled through ferromagnetic grain boundary phase. In the exchange-decoupled Nd-rich Ga-doped sintered magnet, the magnetization reversal is suppressed by thick nonmagnetic grain boundary phase. The EBSD revealed 11° misalignment of 2:14:1 grains in the standard sintered magnet, while higher misalignment of 18° was found in the exchange-decoupled Nd-rich Ga-doped magnet. Micromagnetic simulations incorporating such microstructural features reproduced experimentally observed demagnetization curves fairly well including the enhancement of the coercivity and the deterioration of the squareness in the exchange decoupled sintered magnet.
Source: openaire · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Magnetic Properties of Alloys · Magnetic properties of thin films · Magnetic and transport properties of perovskites and related materials
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (34)
Show source-provided references
1. Effect of carbon on the coercivity and microstructure in fine-grained Nd-Fe-B sintered magnet10.1016/j.actamat.2014.10.047 ↗
2. Corrosion resistance analysis of sintered NdFeB magnets using ultrasonic-aided EDM method10.1007/s11665-014-1298-8 ↗
3. Neodymium-iron-boron permanent magnets10.1016/0304-8853(91)90812-O ↗
4. High-coercivity Nd-Fe-B magnets obtained with the electrophoretic deposition of submicron TbF3 followed by the grain-boundary diffusion process10.1016/j.actamat.2016.06.003 ↗
5. Toward ultimate Nd-Fe-B permanent magnets
6. Preparation of sintered Nd-Fe-B magnets by pressless process10.1134/S0031918X12040096 ↗
7. The influence of Ga-substitution on the coercivity of Nd-(Fe, Co)-B sintered permanent magnets10.1109/20.104917 ↗
8. Preparation and TEM-study of sintered Nd18Fe74B6Ga1Nb1 magnets10.1109/20.281024 ↗
9. Improvement of thermal stability of Nd-Dy-Fe-Co-B sintered magnets by additions of Al, Nb and Ga10.1109/TMAG.1987.1065287 ↗
10. Effect of Ga addition to NdFeCoB on their magnetic properties10.1063/1.98773 ↗
11. Formation of non-ferromagnetic grain boundary phase in a Ga-doped Nd-rich Nd-Fe-B sintered magnet10.1016/j.scriptamat.2015.10.042 ↗
12. K. Nakajima and T. Yamazaki, Japan Patent JP5767788 (2015).
13. Structure and chemical compositions of the grain boundary phase in Nd-Fe-B sintered magnets10.1016/j.actamat.2016.05.035 ↗
14. Grain boundary and interface chemistry of an Nd-Fe-B based sintered magnet10.1016/j.actamat.2011.10.043 ↗
15. Intergrain interaction, coercivity and Henkel plot for NdFeB magnets
16. Theory of nucleation fields in inhomogeneous ferromagnets10.1002/pssb.2221440134 ↗
17. Coey · 2010 · 377
18. On the squareness factor behavior of RE-FeB (RE Nd or Pr) magnets above room temperature10.1109/TMAG.2009.2025190 ↗
19. Coercivity enhancement of HDDR-processed Nd–Fe–B permanent magnet with the rapid hot-press consolidation process10.1016/j.jmmm.2010.08.043 ↗
20. Magnetic domain evolution in Nd-Fe-B: Cu sintered magnet visualized by scanning hard X-ray microprobe10.1016/j.actamat.2016.01.011 ↗
21. Magnetism of ultrathin intergranular boundary regions in Nd-Fe-B permanent magnets10.1016/j.actamat.2014.03.013 ↗
22. Direct observation of ferromagnetism in grain boundary phase of Nd-Fe-B sintered magnet using soft x-ray magnetic circular dichroism10.1063/1.4902329 ↗
23. Magnetism in grain-boundary phase of a NdFeB sintered magnet studied by spin-polarized scanning electron microscopy10.1063/1.4883487 ↗
24. Effect of crystal alignment on the remanence of sintered NdFeB magnets10.1063/1.344828 ↗
25. http://www.cwscholz.net/projects/papers/preprint/schrefl/pamm00/paper_2column.pdf.
26. In-situ high-temperature domain structures of die-upset Nd–Fe–B Magnets10.1016/j.scriptamat.2015.08.017 ↗
27. Strategic coating of NdFeB magnets with Dy to improve the coercivity of permanent magnets10.12989/amr.2015.4.4.227 ↗
28. The demagnetizing field of a nonuniform rectangular prism10.1063/1.3385387 ↗
29. Coercivity generation of surface Nd2Fe14B grains and mechanism of fcc-phase formation at the Nd/Nd2Fe14B interface in Nd-sputtered Nd–Fe–B sintered magnets10.1063/1.2952556 ↗
30. Overview of Nd-Fe-B magnets and coercivity (invited)10.1063/1.361565 ↗
31. Microstructure of fine-grained Nd-Fe-B sintered magnets with high coercivity10.1016/j.scriptamat.2011.05.006 ↗
32. Distribution of Dy in high-coercivity (Nd,Dy)–Fe–B sintered magnet10.1016/j.actamat.2011.01.046 ↗
33. Grain boundary phenomena in NdFeB-based hard magnetic alloys
34. The role of the exchange interaction in nanocrystalline isotropic Nd2Fe14B-magnets10.1016/S0304-8853(98)00239-X ↗