Growth of Bi and Ga Substituted YIG and LuIG Layers by LPE Method

Bi substituted Y- and Lu- iron garnets are very good materials for different kinds of magneto-optical applications. In this work we report the preparation of Bi,Ga: YIG and Bi,Ga: LuIG layers on Gd-Ga garnet (GGG) substrates grown by conventional, isotherm dipping LPE technique using PbO-Bi2O3-B2O3 system as a solvent. Electron microprobe analyses of the garnet films were performed by means of energy-dispersive spectrometer and the refractive index of the layers was determined by spectroscopic ellipsometry. The layer growth rate (vL), saturation magnetisation (4πMS) and the Bi content of the layers were determined as a function of the supercooling of the melt (ΔT) and of the substrate rotation rate (ω) at a given melt composition. From these data the ΔvL/ΔT, Δ4πMS/ΔT, Δ4πMS/Δ(ω)1/2, ΔBi/ΔT and ΔBi/Δ(ω)1/2 growth coefficients were calculated. The physical parameters of the films (thickness, 4πMS, refractive index, Faraday rotation and the figure of merit) can be very sensitively changed by these growth coefficients. The Faraday rotation (ΦF) of our Y2.5Bi0.5Fe3.8Ga1.2O12 and Lu2Bi1Fe4.1Ga0.9O12 garnet layers is ∼4.8 x 103 and ∼8.3 x 103deg/cm at 633 nm wavelength, respectively.