Magnetization and FMR studies of crystal-ion-sliced narrow linewidth gallium-doped yttrium iron garnet

Abstract

Recent interest in employing single-crystal yttrium iron garnet (YIG) films for miniaturized microwave integrated circuit applications has prompted us to study detaching liquid phase epitaxy (LPE) grown YIG films from their gadolinium gallium garnet (GGG) substrates via crystal ion slicing (CIS). We report studies of magnetization and ferromagnetic resonance (FMR) of narrow linewidth gallium-doped YIG (GaYIG) films in various stages of separation from their 〈111〉 oriented GGG substrates. All samples were diced from the same three-inch wafer of Y3Fe4.6Ga0.4O12 with 4πMeff of 1070 G and 9.45 GHz FMR linewidth of 0.4±0.1 Oe. The CIS separation process involved (1) implantation with helium ions, (2) flash annealing to remove surface damage, and (3) chemical etching to detach the YIG at the implantation damaged layer. The starting films were 10.8-μm thick. Separation occurred 7 to 8 μm from the front surface in the YIG. The implantation (5×1016 cm−2 dosage, 3.8 MeV bias) increased the uniaxial anisotropy of these films. A small cubic anisotropy (∼5 G 60° in-plane periodicity) persisted in both implanted and unimplanted samples. Upon implantation the FMR linewidth increased from 0.4 to 3±0.5 Oe. The detached samples have linewidths ranging from 1.7 to 2.5 Oe. The temperature dependence of the linewidths is roughly exponential decreasing as the temperature is lowered for the unprocessed sample, increasing with reduced temperature for all processed samples. Post-detachment annealing restores the FMR linewidth to 0.55±0.5 Oe.