Thermomagnetization characteristics and ferromagnetic resonance linewidth broadening mechanism for Ca-Sn Co-substituted YIG ferrites

Yttrium iron garnet (YIG) ferrites own significant applications in microwave magnetic devices, such as circulators, isolators and filters. The excellent performance and reliability of these devices are strongly dependent on the saturation magnetization (Ms), ferromagnetic resonance (FMR) linewidth (ΔH), dielectric loss tangent (tan δε) and Curie temperature (Tc) of the garnet ferrites. Here, we fabricate Ca-Sn co-substituted Y3-xCaxFe5-xSnxO12 (x = 0.0, 0.1, 0.2, 0.3 and 0.4) ferrites using solid-state reaction method, and investigate the thermomagnetization characteristics of Brillouin function and FMR linewidth based on Néel model of ferrimagnetism and spin wave approach, respectively. This study clarifies the intrasublattice molecular-field coefficients ωaa, ωdd and intersublattice coefficients ωad = ωda. More importantly, we propose an accurate formula of Curie temperature Tc for garnet ferrites. Furthermore, Ca-Sn co-substitution can tailor the FMR linewidth based on the adjustment of anisotropy and the realization of densification. Finally, Y2.7Ca0.3Fe4.7Sn0.3O12 ferrite exhibits optimized magnetic property: 4πMs = 2073 Gs, ΔH = 42 Oe, Tc = 491 K.