“…Therefore, collectively excited modes (i.e., magnons) in ferromagnets or ferrimagnets, being coupled to elementary excitations of electromagnetic waves (photons), have increasingly been studied in a variety of hybrid structures of two or more different systems [4][5][6][7][8][9][10][11][12]. In particular, the rapid development of both spintronics and the design/fabrication technologies of microwave resonators has stimulated further studies of photon-magnon coupling using a low-damping magnetic material, e.g., yttrium iron garnet (YIG: Y3Fe5O12), and high-quality microwave resonators [13][14][15][16][17][18][19][20][21]. In earlier studies, the interaction (coupling) between the photon and magnon modes usually has been demonstrated by showing the modes' splitting at and near their common resonant frequency within the so-called anti-crossing or the level repulsion of two coupled modes [13][14][15][16][17][18][19][20][21].…”