Effect of Aliovalent Substitution in Y2.9Bi0.1Fe₅O₁₂: Magnetization Dynamic Study

摘要

Multifunctional multiferroic materials, such as rare-earth-doped yttrium iron garnet (YIG), are advantageous for low-energy-consumption devices. In this work, we investigated aliovalent (Ce ^{4+ ) substitution in Y _2.9 Bi _0.1 Fe ₅ O ₁₂ ferrite with different compositions Y _2.9-x Ce _x Bi _0.1 Fe ₅ O ₁₂ ( $x =0.0$ , 0.2, 0.4), respectively. The ferrites were fabricated by a conventional solid-state reaction method, and their structural, static, and dynamic magnetic properties were studied at room temperature. The X-ray diffraction (XRD) pattern confirmed the $Iaar {3}d$ cubic phase of all the ferrite compositions together with ceric oxide (CeO ₂ ) as a residual phase containing aliovalent ions. The lattice parameter “ $a$ ” of synthetic garnets decreases linearly with Ce concentration. From the static magnetic measurements, we observed that the saturation magnetization $(4pi M_{S})$ decreases due to combined effect of Ce 3+ paramagnetic ions and Ce 4+ diamagnetic aliovalent ions. Magnetization dynamics have been studied by ferromagnetic resonance (FMR) technique in flip-chip geometry on the coplanar waveguide. Field sweep FMR spectra revealed that the microwave absorption in the $X$ -band and the Ku -band decreases with Ce concentration due to a decrease in the super-exchange interaction between Fe ions at [a] and (d) sites due to electronic transition of Ce 3+ ion. A major investigation of this study shows a decrease in the Gilbert damping constant ( $lpha $ ) from $1.6imes {10}^{-3}$ to $1.52imes {10}^{-3}$ and increase in extrinsic contribution $Delta ({H}_{O})$ to the FMR linewidth $Delta {(H)}$ from 0.38 to 0.54 kOe with Ce concentration. Therefore, this investigation opens a door for the next generation magneto-electric, magneto-optic, and magneto-diele}