Iron, nickel and zinc stoichiometric influences on the dynamic magneto-elastic properties of spinel ferrites

The influence of iron, nickel and zinc stoichiometry on dynamic magneto-elastic properties of Ni0.5Zn0.5Fe2O4 spinel ferrites has been studied. The lattice parameters and the Curie temperatures were accurately measured. Both depend linearly on the iron, nickel and zinc stoichiometry and a linear relation was found between these two parameters. An ionic model is proposed. The effect of the stress on the magnetic dynamic permeability on polycrystalline toroidal samples is evaluated through measurements in a coaxial wave guide between 1 MHz and 6 GHz and with an applied stress in the range 0–20 MPa. The stress is applied along the tore axis. This materials family has a negative magnetostriction coefficient. Increasing the stress and the permeability drastically decreases at low frequencies (wall displacement) and increases at higher frequencies (gyromagnetism). The most important effect is observed for stoichiometric material. All the results could be consistently explained in terms of variation of anisotropy.