Large magnetic anisotropy in lanthanum M-type hexaferrites

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Unit cell of LaFe12O19 hexaferrite. The five nonequivalent Fe sites are octahedral (2a), bipyramidal (2b), tetrahedral (4f1), octahedral (4f2), and 12k. The three- and six-fold local axis are parallel to the hexagonal axis c of the crystal, which is also the easy axis of magnetization.
Unit cell of LaFe12O19 hexaferrite. The five nonequivalent Fe sites are octahedral (2a), bipyramidal (2b), tetrahedral (4f1), octahedral (4f2), and 12k. The three- and six-fold local axis are parallel to the hexagonal axis c of the crystal, which is also the easy axis of magnetization.

CMI researchers at Ames Laboratory conducted the research for this highlight

Innovation 
Application of an ab-initio modeling to double the magnetocrystalline anisotropy of M-type strontium hexaferrite (SrM) via non-critical element, La, substitution. 

Achievement
Developed a localized electronic structure mechanism and predicted both the insulating behavior and the origin of the very large magnetocrystalline anisotropy (double than that of  SrM) in lanthanum M-type hexaferrite (LaM).
 
Significance and Impact

  • Localized electronic structure mechanism correctly predicts magnetocrystalline anisotropy of insulating permanent magnet oxides.
  • Identified site substituted LaM formulation uplifts permanent magnet performance.
  • Potential improvement of magnetization via small substitution of Co in LaM.

Hub Target Addressed 
Win industry adoption of three technologies related to materials substitution for rare earth magnet materials.