Soft and hard natures of Nd2Fe14B permanent magnet explored by first-order-reversal-curves

Po An Chen, Chao Yao Yang, Shu Jui Chang, Min Han Lee, Nai Kuang Tang, Sheng Chan Yen, Yuan Chieh Tseng*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Two commercial Nd2Fe14B samples, MQP-B and sintered-NdFeB were investigated using synchrotron-based x-ray diffraction and first-order-reversal-curves (FORCs). Despite differing in magnetic and structural properties, the two samples were found to comprise two major ferromagnetic components in FORCs. For the sintered-NdFeB case, the soft component may originate from the intrinsically soft Nd-f site which was coupled with its local Fe atomic environment that differs in magnetic anisotropy from the Nd-g site (intrinsically hard). It may directly originate from the Nd-rich phase or microstructural imperfection, while the former possibility (Nd-f site) appears greater than the latter. While for the MQP-B, the minor second phase resulting from high structural disorder was likely in charge of the presence of the soft component. Sophisticated FORCs analyses revealed the natures of the soft and hard components, soft-hard coupling and switching reversibility of the two cases, irrespective of the origins of their two components. This provides insights to the origin of magnetic stability and reversal dynamics of Nd 2Fe14B that have not been fully understood by conventional magnetic analyses. The coexistence of the two components led to an incoherent reversal undermining the magnetic stability of Nd2Fe14B. This is a fundamental problem as to why the performance extremity can only be improved finitely through extrinsic tuning. From FORCs simulation we understand that the soft-hard coupling was moderate in a real Nd2Fe 14B compound. A stronger soft-hard coupling is necessary to conquer the anisotropic competition to enable a coherent reversal that will promote the magnetic hardness.

Original languageEnglish
Pages (from-to)45-53
Number of pages9
JournalJournal of Magnetism and Magnetic Materials
StatePublished - 1 Jan 2014


  • Crystal structure
  • Magnetic materials
  • Magnetic properties
  • Magnetic structure

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