Magnetic anisotropy of Y-type ferrites: Role of the local lattice structure

Abstract

We study magnetic anisotropy (MA) of the Y-type ferrites using an electron theory at 0 K that was previously applied to M-type and spinel ferrites. In our calculation, we consider the local lattice structure around M2 + ions in the ferrites (M2Y ferrites), where M represents Fe, Co, Ni and Cu. The calculated MA energy, difference between magnetic energies of states with magnetisation Ms parallel and perpendicular to c-axis of the hexagonal lattice, is compared with the experimental values by identifying possible occupation sites of M2 +. The calculated MA energies of Co2Y and Ni2Y are − 0.33 and − 0.39 MJ m−3, respectively. The negative sign indicates that Ms is within the c-plane of the lattice. We have analyzed in detail how the local lattice structure around M2 + affects the MA of the M2Y ferrites. The c-plane MA constant K3 of Co2Y is also calculated and compared with the experimental value. In addition, the MAs of Mg2Y and Zn2Y are examined. The findings of this study may contribute to design Y-type ferrites which are applicable to hyper-frequency regime.