Generation of Circulating Cavity Magnon Polaritons

International audienceWe experimentally realize circularly polarized unidirectional cavity magnon polaritons in a torus-shaped microwave cavity loaded by a small magnetic sphere. At special positions, the clockwise and counterclockwise modes are circularly polarized, such that only one of them couples to the magnet, which breaks the mode degeneracy. We reveal the chiral nature of the spectral energy and angular-momentum flow by observing and modeling nonreciprocities of the microwave scattering matrix