Achievement of high coercivity in Sm(Fe0.8Co0.2)12 anisotropic magnetic thin film by boron doping

H. Sepehri-Amin, Y. Tamazawa, M. Kambayashi, G. Saito, Y. K. Takahashi, D. Ogawa, T. Ohkubo, S. Hirosawa, M. Doi, T. Shima, K. Hono

Research output: Contribution to journalArticle

Abstract

SmFe12-based compounds have been considered as promising candidates for next generation permanent magnet materials because of their excellent intrinsic hard magnetic properties with a minimum usage of rare earth elements. However, realizing high coercivity in anisotropic microstructure is a big challenge, which hinders their practical applications. In this work, a novel anisotropic granular microstructure of Sm(Fe0.8Co0.2)12 with a sufficiently large coercivity (µ0Hc) of 1.2 T and with a high remanent magnetization of 1.50 T is demonstrated in thin films prepared by co-sputtering Sm(Fe,Co)12 with boron. Detailed microstructure characterization using high resolution scanning transmission electron microscopy (STEM) and atom probe tomography (APT) indicate that the addition of B leads to the development of columnar-shaped Sm(Fe0.8Co0.2)12 grains with a size of ∼40 nm, which are surrounded by ∼3 nm-thick B-enriched amorphous intergranular phase. Domain wall pinning at the amorphous grain boundary phase is attributed to the high coercivity. This work provides a guiding principle for realizing high-coercivity anisotropic SmFe12-based permanent magnets, which can outperform Nd-Fe-B magnets and could be used as the next-generation high-performance permanent magnets in various applications.

Original languageEnglish
Pages (from-to)337-342
Number of pages6
JournalActa Materialia
Volume194
DOIs
Publication statusPublished - 2020 Aug 1
Externally publishedYes

Keywords

  • Coercivity
  • Higher performance permanent magnets
  • Nanostructured
  • Sm(FeCo)B
  • Thin magnetic film
  • ThMn-type structure

ASJC Scopus subject areas

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

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    Sepehri-Amin, H., Tamazawa, Y., Kambayashi, M., Saito, G., Takahashi, Y. K., Ogawa, D., Ohkubo, T., Hirosawa, S., Doi, M., Shima, T., & Hono, K. (2020). Achievement of high coercivity in Sm(Fe0.8Co0.2)12 anisotropic magnetic thin film by boron doping. Acta Materialia, 194, 337-342. https://doi.org/10.1016/j.actamat.2020.05.026