Vacancy-engineered Gd3+-substituted yttrium iron garnet with narrow ferrimagnetic linewidth and high Curie temperature

With the urgent need for high-power low-loss microwave systems, next-generation wireless communications call for high-performance yttrium iron garnet with narrow ferrimagnetic resonance (FMR) linewidth, large spin-wave linewidth, and high Curie temperature, which can be tailored by cation substitution and vacancy engineering. Here, the electromagnetic properties of vacancy-engineered Gd3+-substituted garnet ferrites are reported. Cation vacancies on the dodecahedral sites of the garnet crystal structure are introduced by deficient Gd3+ substitution for the Y3+ ions. The polycrystalline microstructure, magnetic properties, and electrical properties of both the Gd3+-sufficient and Gd3+-deficient samples are comprehensively examined and compared. The deficient Gd3+ substitution promotes the densification process and grain growth during the sintering stage. Without detriment to the spin-wave linewidth and electrical resistivity, the vacancies are beneficial to reducing the FMR linewidth and increasing the Curie temperature. With appropriate vacancy concentrations, the garnet ferrite samples exhibit a 58% reduction in the FMR linewidth and a 13% increase in the Curie temperature. These results reveal the great potential of the vacancy-engineered Gd3+-substituted garnet ferrites for high-power low-loss microwave communication systems.