[110]-Directed Ridge Formation of Epitaxial Y₃Fe₅O₁₂ Film Grown on [111]-Oriented Gd₃Ga₅O₁₂

An epitaxially grown Y 3 Fe 5 O 12 (YIG) film on a [111] oriented Gd 3 Ga 5 O 12 (GGG) substrate is processed to form a [110]-directed ridge pattern by argon ion-beam etching and subsequent soaking in phosphoric acid solution. The appearance of (210) faces strongly depends on the temperature at which the film is soaked in the solution. The etch rate of YIG film in the solution is about half that of GGG. A GGG perpendicular side wall is obtained under the YIG ridge after soaking at 140°C for 13 min. A circular near-field intensity pattern is observed at λ=1.55 µm for a 3-µm-wide buried YIG waveguide which is prepared by an ion-beam etching process with soaking in the solution.