Magnetocrystalline anisotropy study of Co-substituted M-type strontium hexaferrite single crystals

The study on the magnetocrystalline anisotropy (MA) of La-Co co-substituted strontium hexaferrite (La-Co SrM) shows a joint effect of Fe2+ and Co2+ ions in the enhancement of MA. Since the role of Fe2+ single ion has been studied with La-substituted strontium ferrite, in this work, Co-substituted strontium hexaferrite SrFe12-xCoxO19 (Co-SrM) single crystals were successfully grown for 0 <= x <= 0.31 by the Na2CO3 flux method to elucidate the anisotropy of Co2+ single ions. Co-substitution in this preparation condition has a limit solubility of 0.31 and enhances uniaxial magnetic anisotropy field HA by 19% for 0.03 = x <= 0.11, with a mere loss of 7% of saturation magnetization MS at 5 K. The enhanced HA of Co-SrM is reported for the first time, even higher than that of La-Co SrM, which is suitable to be used as permanent magnets in this concentration range. But with the further sub-stitution of Co, the planar anisotropy of x = 0.31 was observed at 5 K. The potential nonlinear magnetic structure of Co-SrM remains to be discovered for magnetoelectric effects. This work is also of great significance as a complement to the magnetocrystalline anisotropy study of La-Co SrM.

Automated summary

The study demonstrates the enhancement of magnetocrystalline anisotropy (MA) in La-Co co-substituted strontium hexaferrite (La-Co SrM) due to the joint effect of Fe2+ and Co2+ ions. Co-substituted strontium hexaferrite SrFe12-xCoxO19 (Co-SrM) single crystals were grown to investigate the anisotropy of Co2+ single ions. The solubility of Co in this preparation condition is limited to 0.31, and for 0.03 < x <= 0.11, a 19% enhancement in uniaxial magnetic anisotropy field HA is observed, with only a 7% loss in saturation magnetization MS at 5 K. The enhanced HA of Co-SrM is even higher than that of La-Co SrM, making it suitable for use as permanent magnets in this concentration range. However, for x = 0.31, planar anisotropy is observed at 5 K. The potential nonlinear magnetic structure of Co-SrM remains to be discovered for magnetoelectric effects. This work serves as a significant complement to the magnetocrystalline anisotropy study of La-Co SrM.