LPE GROWTH OF YLaTm AND YLaEu GARNET FILMS

Abstract

The growth of films of the composition Y3–(x+y)LaxRyFe5–zGazO12, where R = Tm or Eu, on GGG substrates by liquid phase epitaxy from a PbO–B2O3 fluxed melt is described. Highly uniform, low defect density films have been grown by means of horizontal dipping using intermittent substrate rotation in conjunction with a novel substrate holder. A furnace with three separate temperature zones was used to optimize the vertical temperature profile. Incorporation of La into the films allows compositions containing Tm to be made whose lattice parameters are matched to GGG and compositions which contain Eu to be made with smaller Eu concentrations than were previously possible. The compositions grown, which contain only trivalent cations, exhibit growth induced anisotropy, high mobility, low coercivity, and sufficient magnetostriction to allow ion implantation to effectively suppress hard bubble formation. Detailed measurements of saturation temperature as a function of oxide concentration show that the La ion contributes differently to the garnet phase than do other commonly used rare earth cations. The kinetics of melt equilibration have been studied and procedures to equilibrate the melt to ensure reproducible film growth are described. Electron microprobe analysis has been used to determine the La distribution coefficient as a function of La concentration, the growth rate of the film, and the melt temperature.