New bubble garnet films with orthorhombic magnetic anisotropy and high mobility: (YBi)3(FeGa)5O12 and (YTmBi) 3(FeGa)5O12/(110)GGG

Abstract

New orthorhombic magnetic anisotropy garnet liquid phase epitaxial films with high mobility and low coercivity, (YBi)3(FeGa)5O 12 and (YTmBi)3(FeGa)5O12/(110)GGG, have been successfully obtained. There are no hard bubbles, and wall states are either S = 0, 1, or -1. For 2 μm bubble material (YBi)3(FeGa) 5O12/(110)GGG, mobility is μw = 85 m/s Oe and saturation velocity is Vs ≃130 m/s. For 6 μm bubble material (YTmBi)3(FeGa)5O12/(110)GGG, μw = 23 m/s Oe and Vs ≃130 m/s are observed. Vs ≃130 m/s for 2 μm bubble material assures bubble transfer at more than 10 MHz in a current access dual conductor device and utilization of the material for a magneto-optic readout head. Orthorhombic anisotropy for these materials is mostly growth induced. Growth-induced perpendicular anisotropies are not observed for eight other garnet systems on the (110)-GGG. Growth-induced orthorhombic anisotropy energy for Bi containing garnets is discussed using Gyorgy's phenomenological parameters, A and B, compared with growth-induced anisotropy for (111)-oriented garnet films. A unique behavior of Y3+ in Bi containing garnets supports perpendicular anisotropy for orthorhombic anisotropy materials.