EFFECTIVE ANISOTROPY IN POLYCRYSTALLINE MATERIALS . SEPARATION OF COMPONENTS

A method is proposed to determine the over-all anisotropy K in ferrimagnetic materials from initial susceptibility of single-domain grain samples. Indications on technology of single-domain grain samples are given. The Ni1-xZnxFe2O4 system is studied in detail. The upper limit of the contribution from dipolar energy has been determined by studying Mn0.5Zn0.5Fe2O 4 and is found to be negligible. The study of magnetoelastic anisotropy has been carried out on compositions of known K1. This anisotropy (expressed as λsσ) varies very little at low temperatures depending on Zn content, and for a given composition it varies as λs. Thus, σ is temperature independent. σ is shown to be an intrinsic property for a composition and it increases with Zn content. Our investigations show that realization of single-domain grain samples enables us to obtain σ and K1 from measurements of (μ - 1) c, Ms, and λs, which are easily accessible from polycrystalline samples. © 1968 The American Institute of Physics.