1 μmバブルを用いたイオン注入バブル素子用ビスマス置換ガーネット膜

抄録

Garnet LPE films containing bismuth which support 1 μm bubbles have been grown on (111) GGG substrates. Gallium substituted garnets, such as YSmTmBiGa, YTmBiGa and LaSmLuGa films, have good properties at room temperature, e.g., low damping, small collapse field (H_co1) and small crystalline anisotropy constant (|K₁|). These films are not suitable for bubble propagation at higher temperatures because of too low Curie temperature (T_c) after ion implantation. On the other hand, calcium germanium substituted garnets, such as GdSmTmBiCaGe and YSmTmBiCaGe have higher T_c and larger negative magnetostriction coefficient, λ₁₁₁. However, Q factor or characteristic length (l) is restricted by small Sm³⁺ contents in these films. By substituting Si⁴⁺, instead of Ge⁴⁺, we can get much room to adjust the film properties. GdSmLuBiCaSi films have zero temperature dependence of H_co1. Temperature coefficient of H_co1 for YGdSmLuBiCaSi is −0.2%/°C Atomic compositions for BiCaSi substituted films are analyzed. Y³⁺ and Lu³⁺ are partially substituted into a-site. Distribution coefficients for Y³⁺, Gd³⁺, Sm³⁺ and Lu³⁺ are estimated.