Growth and Enhancement of Magneto-Optical Properties in the Dysprosium-Doped Large-Size Yttrium Iron Garnet Crystal

The growing demand for nonreciprocal optical devices has intensified the need for high-performance magneto-optical materials. Yttrium iron garnet (YIG) stands out for its excellent magnetic and magneto-optical characteristics. In this work, centimeter-sized dysprosium-doped YIG single crystals were successfully synthesized via the top-seeded solution growth method. The integration of Dy 3+ ions significantly reduces both coercivity and saturation magnetization compared with pure YIG, enabling magnetic saturation under lower external fields. The as-grown crystal exhibits ferrimagnetic behavior with a saturation magnetization of 9.96 emu/g and a coercivity of 8.40 Oe. Postgrowth oxygen annealing effectively suppresses Fe 2+ and oxygen vacancy defects, further improving the magneto-optical performance. After annealing at 900 °C, the defect concentration is minimized, leading to a reduced coercivity of 5.09 Oe. Moreover, the treated crystal shows enhanced optical transmittance (71.93% at 1550 nm, 76.05% at 2000 nm), and the Faraday rotation angle increased by more than 12% (184°/cm at 1550 nm, 123°/cm at 2000 nm). These results highlight the essential role of oxygen annealing in optimizing crystal quality and magneto-optical functionality, thus providing critical insights for the property design and postprocessing of magneto-optical materials.