Growth, optical dispersion and magnetic behavior of Dy3+ doped yttrium iron garnet crystals

Y3Fe5O12 (YIG) crystals are highly desirable for the fabrication of mid-infrared isolators with the rapid growth of optical communications, although it is rather challenging to grow large size and high-quality single crystals. Dy3+ doping is expected to improve the optical and magneto-optical properties. However, high quality Dy:YIG crystals and the adjustment of Dy3+ on the structure and optical behavior of YIG crystal remain unclear, impeding its practical applications. Herein, a series of Y3–xDyxFe5O12 (x = 0, 0.5, 1.0, 1.5, 3) solid solution crystals was grown by the flux-Bridgman method and single crystals up to 25 mm were obtained. With the introduction of Dy3+, lattice parameters are gradually enlarged from 1.2379 nm (YIG) to 1.2420 nm (DyIG). Typical Dy3+ absorption peaks are observed around 1070, 1265 and 1670 nm. The refractive index decreases from 2.37 (500 nm) to 2.10 (2500 nm) for YIG crystal, and it reduces from 2.47 (500 nm) to 2.16 (2500 nm) for DyIG crystal. The optical bandgaps remain almost unchanged for Dy:YIG crystals. The optical dispersion of the refractive indices was finely fitted by the Wemple and DiDomenico (WDD) and the Sellmeier models, respectively. With the increase of Dy3+ content, the saturation magnetization (Ms) decreases significantly from 23.62 emu/g (YIG) to 5.33 emu/g (DyIG). Small coercive field is persisted for this system, endowing small external magnetic field. These results provide valuable references for the manipulation of rare earths on the properties of magneto-optical crystals, which is beneficial to the design of high-performance garnet crystals for the application of optical switching and non-reciprocal related devices.