Oxygen‐Atmosphere‐Optimized Gyromagnetic Properties of YIG Ferrites for Low‐Loss X‐Band Circulators

ABSTRACT

To meet the urgent need for high‐performance microwave ferrite devices in next‐generation communication systems, a novel approach for improving the gyromagnetic properties of yttrium iron garnet (YIG) by introducing the oxygen atmosphere during pre‐sintering is investigated. The results demonstrated that an appropriate oxygen flow rate (OFR) promoted garnet phase formation; however, an excessively high OFR caused the accumulation of lattice distortion and oxygen defects, resulting in a decrease in phase purity. At OFR = 150 mL/min, YIG ferrites with high saturation magnetization (4π M _s > 1800 Gs) and low microwave losses (Δ H  < 30 Oe and tan δ _ε  < 10 ⁻⁵ ) were obtained. A classic X‐band microstrip circulator based on this material exhibited low insertion loss (< 0.5 dB), high return loss (> 76 dB), high isolation (> 35 dB), and a wide operating bandwidth (∼2 GHz). The aforementioned excellent performance highlights the potential of optimized YIG ferrites for applications in microwave nonreciprocal devices.