Functionalized High-Speed Magnon Polaritons Resulting from Magnonic Antenna Effect

Magnon polaritons (MPs) refer to a light-magnon coupled state, which have the potential to act as infor-mation carriers, possibly enabling charge-free computation. However, light-magnon coupling is inherently weak. To achieve sufficiently strong coupling, a large ferromagnet or coupling with a microwave cav-ity is necessary. Thus, we theoretically propose a 100 nm YIG/1 mu m GGG/500 mu m YIG structure as a fundamental platform for magnonic and magnon-optical information storage devices to address the afore-mentioned issues. Furthermore, we discuss the transport properties of the MPs. Owing to the waveguide modes formed by the dielectric constant of the structure, the magnons placed in a nanometer-thin layer are strongly coupled with light. In addition, a longitudinal magnon-magnon coupling between thin and thick magnetic layers yields rich functionalities and a large magnon density to the thick-layer MPs due to the "magnonic antenna effect." Hence, a large, direction-switchable magnon current in the thin layer is observed. The proposed structure indicates a longer coherence length and suitable figure of merit for the magnonic antenna effect. Therefore, the findings of this study would enable the integration of ferromag-netic micro-and nanostructures for MP-based information devices without any restrictions due to cavities.