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

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Abstract
New orthorhombic magnetic anisotropy garnet liquid phase epitaxial films with high mobility and low coercivity, (YBi)3(FeGa)5O12 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.