レーザ熱処理を用いた誘電体ミラー上の磁性ガーネット薄膜の選択的結晶化

抄録

  One of realization of magnetophotonic crystals (MPCs) has a microcavity structure where a thin magnetic garnet film-bismuth-substituted yttrium iron garnet (Bi:YIG)-is sandwiched between two Bragg mirrors (BMs) made of Ta₂O₅ and SiO₂. For MPCs fabricated by sputtering, annealing of as-sputtered Bi:YIG films is essential for garnet crystallization. However, Ta₂O₅ is also crystalized at garnet crystallization temperatures, when utilizing a conventional annealing in an electric furnace. Ta₂O₅ crystallization worsens optical parameters of BMs and consequently properties of an MPC. To overcome this problem, we selectively annealed as-sputtered Bi:YIG/BM samples by a high power laser. Experiments showed that Bi:YIG can be crystallized while keeping Ta₂O₅ in the amorphous state; this was confirmed by the transmission electron microscopy.