Development of a New Type of Magneto-optical Material: Flexible, Low-Cost, Fe ₃ O ₄ @ZIF-8/PgC ₅ Cu/PMMA with High Figure of Merit

Magneto-optical materials are essential for optical communication devices, yet most crystalline or vitreous media are rigid and have high demands on design and processing. Here we develop a facile multicomponent composite strategy to fabricate a flexible magneto-optical film, Fe 3 O 4 @ZIF-8/PgC 5 Cu/PMMA, where ultrasmall Fe 3 O 4 magnetic units are uniformly embedded in a transparent polymer. The film loaded with 0–1.5 wt % Fe 3 O 4 @ZIF-8/PgC 5 Cu has flexible, readily formable, and high magneto-optical properties while maintaining a high optical transmittance of about 80%. Another encouraging result is that a common magnetic material of Fe 3 O 4 composite is clearly observed to have strong magneto-optical effect. At 0.5 wt %, the figure of merit reaches 6 deg.·dB –1 at 532 nm, exceeding that of Bi:YIG/PMMA (1.46 deg.·dB –1 ). Moreover, the magnetic circular dichroism at 532 nm exceeds 7 times that of commercial crystalline YIG. This work offers a promising strategy to fabricate flexible magneto-optical materials, expanding applications in microscale devices of specific shapes.