Flux growth and magnetic properties of hexagonal ferrite single crystal (abstract)

Abstract

Using a new tenary system flux Bi2O3-BaO-B2O3, the growth of hexagonal ferrite single-crystal BaM and ZnW has been investigated. The flux has a lower melting point and wider growth temperature range. The shape characteristic of the crystals grown has changed from thin platelets to columns. The substitution of diamagnetic ions in hexagonal ferrite has been studied. In order to discuss the origin of magnetic anisotropy in hexagonal ferrites BaM and ZnW, the magnetic anisotropy at each sublattice has been calculated by a well-known H. B. Callen and E. Callen anisotropy model which is given by K1(T)/K1(0) =I1+1/2[Zi(T)]/I1/2[Zi(T)] with Zi(T)=2KT∑nm=1N imSiSmJimσm(T). The magnetization σi(T) and the exchange parameters Jim in different sublattice has been fitted by a least-squares method to the experimental values of the saturation magnetization, according to the molecular field theory. The results show that the contributions of Fe3+ in different sublattices to magnetic anisotropy are different. The strong uniaxial magnetic anisotropy in hexagonal ferrites is attributed mainly to the contribution of ferric ions located in trigonal bipyramidal sublattices 2b BaM and 2b 2b in ZnW. The influence of diamagnetic ions Zn, In, Al substitution for Fe3+ to magnetic anisotropy can be explained by the calculated resultant.