Magnetic, ferromagnetic resonance and electrical transport study of Ni1−xTbxFe2O4 spinel ferrites

The impacts of terbium (Tb) contents on magnetic, ferromagnetic resonance (FMR), electrical and dielectric properties of Ni1−xTbxFe2O4 ferrites were investigated. A vibrating sample magnetometer was employed to probe the magnetic properties of the samples at room temperature. It was found that with the increased terbium content, the coercive force and saturation magnetization were decreased which may be attributed to spin canting. Magnetic dynamics of the samples were studied by ferromagnetic resonance in X band (9.5 GHz) at room temperature. The incorporation of terbium sufficiently lowers the FMR line-width. The decrease in FMR line-width is attributed to the reduction of super-exchange interactions. The DC electrical resistivity and activation energy are higher for the substituted samples. The dielectric constant, dielectric loss (tan δ) and AC-conductivity decreased on account of doping. The decrease in dielectric constant is imputed to the reduction in the internal viscosity of the doped samples. The dielectric data are explained on the basis of space charge polarization. As Ni–Tb ferrites have low value of coercivity, high dielectric constant and low tan δ, they may be attractive for application in switching and memory storage devices.