RF-sputtered Bi-substituted iron garnet composite films for visible-range magnetooptics

We report on the synthesis of new magneto-optical materials with excellent optical and magneto-optical (MO) properties for visible-range and near-infrared applications. Bi-substituted composite garnet films fabricated with excess bismuth oxide content using RF co-sputtering and conventional oven-annealing processes are found to possess simultaneously a record-high MO quality and strong uniaxial magnetic anisotropy. The films demonstrate nearly-square hysteresis loops with specific Faraday rotations of up to 10.1 deg/µm at 532 nm and up to 2.6 deg/µm at 635 nm, which are significantly larger than these measured in garnet films of the same composition prepared without extra bismuth oxide content. Record-high MO figures of merit are demonstrated in our composite garnet materials due to a significant reduction in the optical absorption coefficients achieved across the visible spectral range, thus making garnet-oxide composites highly attractive for use in a range of magneto-optical applications.