Strong photon–magnon coupling at microwave and millimeter-wave frequencies in planar hybrid circuits

Photon–magnon hybrid systems have potential applications in modern information processing technologies. Although planar hybrid circuits based on split ring resonators have shown strong coherent photon–magnon coupling, none of those operates at millimeter-wave frequencies. With specially designed electric-field-coupled resonators, strong coupling between resonator modes and ferromagnetic resonance modes (either in-plane or out-of-plane) was experimentally observed in two circuits working at 4.1 and 30 GHz. Their dynamics were well described by quantum models. The miniature, integrable, and physically robust circuits pave a way for planar photon–magnon hybrid systems at even higher frequencies, demonstrating the possibility to integrate magnon-based systems with millimeter-wave devices.