Physical and microwave characteristics of Gd-doping yttrium iron garnet (YIG)

Ferrimagnetic insulating yttrium iron garnet (YIG) are widely used in microwave devices due to their unique magnetic, electrical and microwave properties. The substitution of rare earth ion for the Y$^{3+}$ ion can modulate or improve its high-frequency properties for microwave application. We prepared a serial of single-phased polycrystalline Y$_{3-x}$Gd$_{x}$Fe$_{5}$O$_{12}$ garnet samples with $x $= -- 3.0 by the conventional ceramic technique. The refinement of X-ray diffraction patterns of the samples shows them to crystallize in a centrosymmetrically cubic structure with a\textit{ Ia3d} space group. Both the lattice constant and dc saturation magnetization at room temperature decrease with increasing Gd$^{3+}$ We also measured the low- and high-frequency dielectric constant and tangent loss. As well, the spin wave line width $\Delta $H$_{k}$ regarding the ferromagnetic resonance behavior is on progress. These results are important to develop high-power circulators and isolators in microwave range.