Narrow Linewidth and High Infrared Transmission in Hydrothermally Grown Yttrium Iron Garnet

Abstract
The properties of yttrium iron garnet (YIG) grown from high‐temperature—high‐pressure aqueous (hydrothermal) solvents have been studied. YIG with a room‐temperature ferromagnetic linewidth as low as 0.3 Oe and with an infrared extinction coefficient at 1.14 μ as low as 0.5 has been prepared. Such YIG should be useful for lasers, laser optical devices, and microwave devices, and the hydrothermal technique is shown to have advantages over conventional flux growth for the reproducible production of large garnets. Linewidth is shown to correlate with proton content which is affected by the concentration of Ca2+ ions in the lattice. Absorbtion at 1.14 μ is uniformly low in hydrothermal YIG, and this fact is discussed. The role of impurities, dopants, and conditions of growth are discussed.