Synthesis of high-quality inverse opals based on magnetic complex oxides: yttrium iron garnet (Y3Fe5O12) and bismuth ferrite (BiFeO3)

Abstract

Magnetophotonic crystals (MPCs) are periodic structures that are made of a magnetic material or have a magnetic defect introduced in a periodic non-magnetic matrix, and possess interesting optical and magneto-optical properties. Of particular interest are three-dimensional (3D) MPCs made of magnetic complex oxides, such as yttrium iron garnet (Y₃Fe₅O₁₂, YIG) and bismuth ferrite (BiFeO₃, BFO). In this paper we report for the first time the synthesis of 3D MPCs with a face-centered cubic (fcc) inverse opal structure based on these materials. The samples were prepared by a sol–gel method that involves infiltration of polystyrene colloidal crystals with liquid precursors followed by a high-temperature annealing. The developed procedure yields high-quality single-phase YIG and BFO inverse opals with high filling fractions of magnetic materials. Optical measurements were performed on large (characteristic size ∼ 100 μm) single crystal domains of inverse opals, and angle-dependent reflectance peaks caused by the Bragg diffraction of light in highly ordered YIG and BFO MPCs were observed. Also, since BFO has a high refractive index (>2.8) and a low extinction coefficient at λ > 550 nm, BFO MPCs with the fcc structure have a potential for the realization of a complete photonic band gap in the visible and near infrared regions.