Synthesis of Al- or Ga-Substituted Bi3Fe5O12 Garnet Films

Using an alternating ion-beam-sputtering technique, Al³⁺ and Ga³⁺ ions were successfully substituted for Fe³⁺ ions in Bi3Fe5O12 (BIG) film. The effects of substitution were confirmed by measurements of the lattice constant, ferromagnetic resonance field and magnetic moment. The lattice constant and saturation magnetization of BIG film can be adjusted by Al or Ga substitution, which is analogous to Al- or Ga-substituted YIG. The magnetic anisotropy of a BIG film can be changed from the easy-plane type to the perpendicular uniaxial type by Al or Ga substitution. The uniaxial anisotropy is mainly attributed to the stress-induced anisotropy.