Enhanced magnetic and optical properties of Y ₃ Fe ₅ O ₁₂ (YIG) films with Au nanoinclusions

Y₃Fe₅O₁₂ (YIG) thin films are well known for their ferrimagnetic insulating property and low Gilbert damping coefficient (<i>α</i>), allowing them to be used for various spintronic applications and as magneto-optical isolators for photonic devices. Instead of doping, incorporation of plasmonic metals as nanoinclusions could be a promising route for improved magneto-optical coupling properties. In this work, YIG-Au nanocomposites have been deposited with ferrimagnetic insulating YIG as the matrix and Au nanoinclusions which introduce plasmonic absorption, optical anisotropy, and hyperbolic properties. Films with varying Au nanoinclusion densities have been processed and annealed to compare with the as-deposited ones. The films that had low Au nanoinclusion density and were annealed presented a lower magnetic damping coefficient of 2.84 × 10^-4 than the pure YIG film (9.66 × 10^-4). The as-deposited film with the highest Au density shows the strongest hyperbolic properties among all samples. These results demonstrate that both magnetic damping and optical properties can be tuned through deposition conditions in YIG-Au nanocomposite thin films, allowing for a balance of both properties. This YIG-Au nanocomposite system presents promising potential in next-generation opto-spintronic devices.