Magnetic properties and ferromagnetic resonance of Li-Mg-Ti microwave ferrite systems (abstract)

Abstract

The magnetic properties and ferromagnetic resonance of the Li-Mg-Ti microwave ferrite system were investigated in this paper.1,2 The chemical compositions of the samples studied were as follows: Li0.44Me0.12(MgTi)xFe2.44−2xO4 where Me represent Ni, Mn, Zn, etc., ions. It was verified by x-ray diffraction spectra that all specimens were of the spinel structure. The lattice constants were linearly increased with the substitution amount of Mg and Ti ions. The saturation magnetizations were measured as a function of composition and temperature. The results of experiments indicate that the saturation magnetizations and Curie temperatures were decreased with the increase of the substituted amount of Mg and Ti ions. The magnetic properties of this ferrite system were as follows: 4πMS≊300–3000 G, Hc≊0.8–1.5 Oe, Br/Bm≥0.8, and ΔH≊66–350 Oe. In the range of 3.6–16.5 GHz, except the composition of x=0, the room-temperature ferromagnetic resonance linewidths ΔH were linearly decreased with lowering frequency, up to 6 GHz. It can be explained by the phenomenological theory of ferromagnetic resonance. Below 4 GHz the resonance linewidths rose steeply. It was caused by the unsaturation effect of the spherical specimen. The resonance linewidths (x≥0.20) and the intensities of the internal magnetic fields (x≥0) were decreased with the increasing Mg and Ti ions, while the g factors were slightly increased. On the basis of the theory of ferrimagnetism and ferromagnetic resonance, the experimental results were analyzed and discussed.