Magnetization reversal of exchange-coupled and exchange-decoupled Nd-Fe-B magnets observed by magneto-optical Kerr effect microscopy

M. Soderžnik, H. Sepehri-Amin, T. T. Sasaki, T. Ohkubo, Y. Takada, T. Sato, Y. Kaneko, A. Kato, T. Schrefl, K. Hono

Research output: Contribution to journalArticle

45 Citations (Scopus)

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 Nd2Fe14B 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.

Original languageEnglish
Pages (from-to)68-76
Number of pages9
JournalActa Materialia
Volume135
DOIs
Publication statusPublished - 2017 Aug 15
Externally publishedYes

Keywords

  • Coercivity
  • Kerr microscopy
  • Magnetic domains
  • Nd-Fe-B magnet

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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