Magnetic state of nickel-zinc ferrites at high zinc concentrations

Neutron diffraction and magnetic methods are used to investigate ferrites from the system Zn_xFe_1−x Ni_1−x Fe_1+x ]O₄. In these investigations, no diffraction effects were observed that would indicate ordered positions for the perpendicular projections of spins at 4.2 K over the entire ferrimagnetic range of concentrations x. However, the high-field magnetic susceptibility and intense small-angle scattering of neutrons observed at helium temperatures in samples with x>0.45 are evidence of local angular structures with effective sizes of 1–10 nm. The temperatures at which these local angular structures are disrupted are determined. Fiz. Tverd. Tela (St. Petersburg) 40, 1503–1504 (August 1998)