Anisotropy of rare-earth magnets

R. Skomski, David J Sellmyer

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Rare-earth intermetallics such as Nd2Fe14B and Sm-Co are widely used as high-performance permanent magnets, because they combine high magnetocrystalline anisotropy with reasonable magnetization and Curie temperature. The anisotropy is a combined effect of spin-orbit coupling and electrostatic crystal-field interactions. The main contribution comes from the rare-earth 4f electrons, which are well-screened from the crystalline environment but exhibit a strong spin-orbit coupling. In this limit, the magnetocrystalline anisotropy has a very transparent physical interpretation, the anisotropy energy essentially being equal to the energy of Hund's-rules 4f ion in the crystal field. The corresponding expression for the lowest-order uniaxial anisotropy constant K1 is used to discuss rare-earth substitutions, which have recently attracted renewed interest due to shifts in the rare-earth production and demand. Specific phenomena reviewed in this article are the enhancement of the anisotropy of Sm2Fe17 due to interstitial nitrogen, the use of Sm-Co magnets for high-temperature applications, and the comparison of rare-earth single-ion anisotropy with other single-ion and two-ion mechanisms.

Original languageEnglish (US)
Pages (from-to)675-679
Number of pages5
JournalJournal of Rare Earths
Volume27
Issue number4
DOIs
StatePublished - Jan 1 2009

Fingerprint

Rare earths
Magnets
Anisotropy
anisotropy
Ions
Magnetocrystalline anisotropy
ion
Orbits
Crystals
High temperature applications
Curie temperature
crystal
Permanent magnets
Intermetallics
Electrostatics
Magnetization
Substitution reactions
Nitrogen
magnetization
Crystalline materials

Keywords

  • crystal-field interaction
  • interstitial modification
  • magnetic anisotropy
  • permanent magnets
  • rare earths
  • spin-orbit coupling

ASJC Scopus subject areas

  • Chemistry(all)
  • Geochemistry and Petrology

Cite this

Anisotropy of rare-earth magnets. / Skomski, R.; Sellmyer, David J.

In: Journal of Rare Earths, Vol. 27, No. 4, 01.01.2009, p. 675-679.

Research output: Contribution to journalArticle

Skomski, R. ; Sellmyer, David J. / Anisotropy of rare-earth magnets. In: Journal of Rare Earths. 2009 ; Vol. 27, No. 4. pp. 675-679.
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