Magnetic Anisotropy of Co-substituted Bi-DyAllG Nanoparticles

Abstract

The magnetic properties of the superparamagnetic Co-substituted Bi-DyAJIG (BiDy₂Co_xAl_yFe_5-x-yO₁₂: 0≤x≤0.2, 0≤y≤1.1) nanoparticles were investigated. On the basis of the magnetic data, it is inferred that the magnetic moments of Dy ions cant from those of the iron ions. The canting angle was estimated to be 53°, which is larger than that previously observed in the sputtered films. The reason of the canting is possibly the surface and/or size effect of the nano-size garnet particles. The Co substitution was found to be effective to increase the coercive-force of the nanoparticles for magnetic recording storage media. The bifurcation temperature of zero-field-cooled (ZFC) and field-cooled (FC) magnetizations is also increased by the Co substitution. The ZFC and FC magnetization curves for the BiDy₂Co_xAl_y, Fe_5-x-yO₁₂ nanoparticles suggest that Co substitution enhances magnetic anisotropy of the nanoparticles, which is in accordance with increase in coercive-force Hc.