Q factor of dual-tunable microwave resonators based on yttrium iron garnet and barium strontium titanate layered structures

Q factor of dual-tunable ferrite-ferroelectric hybrid wave microwave resonator was studied as a function of bias electric voltage U and bias magnetic field H. The resonator consisted of a thin (7μm) ferromagnetic resonator made of a single-crystal yttrium iron garnet film and a dielectric resonator made of relatively thick (500μm) plate of ceramic barium strontium titanate having similar in-plane sizes. A frequency spectrum of the resonator consisted of two hybridized modes: a quasiferromagnetic mode and a quasidielectric mode. Maximum electric tuning band of 5% of the resonance frequency has been observed for H values corresponding to maximum hybridization of the modes. The Q factor of the resonator was varied from 30–300 depending on both U and H. In general, Q factor decreases with increasing level of modes’ hybridization and electric tuning interval. Thus, Q factor and electric tunability are competing characteristics of hybrid ferrite-ferroelectric microwave resonators.