Synergistic modulation of magnetic and dielectric properties in high-Bi-content garnet ferrites

Garnet-type ferrites Bi 1.2 Ca 3 x Y 1.8–3 x Zr x V x Fe 5–2 x O 12 ( x  = 0.1–0.6) were synthesized via solid-state reaction, with Bi–Ca ions predominantly occupying dodecahedral c-sites. The phase stability and microstructure were significantly improved through Ca-Zr-V multi-ion doping, which served as the foundation for excellent magnetic and dielectric properties. The dielectric constant (ε r > 22) was increased by the strong spin-orbit coupling and high polarizability of Bi 3 + . The Bi 3+ -induced magnetocrystalline anisotropy was suppressed by Zr 4+ and V 5+ , which lowered the ferromagnetic resonance (FMR) linewidth (ΔH) to 73.06 Oe. Grain refinement shortened the spin-wave propagation path, leading to a maximum spin-wave linewidth (ΔH k ) of 13.10 Oe. At x  = 0.50, optimal properties were achieved (ε r = 22.43, tanδ ε = 1.26 ×10 - 3 , ΔH = 73.06 Oe, ΔH k = 10.30 Oe, M s = 15.60 emu/g), and the synergistic optimization of high dielectric constant, low loss, and broad spin-wave linewidth was realized for the first time in ferrites for miniaturized circulators.