A Magnon-photon interface based on Van der Waals Magnetic semiconductor

Coherent control of light with electron spins represents a fundamental goal across multiple research fields, such as opto-spintronics, chiroptics, quantum information. In a magnetic-ordered material, coherent magnon gives rise to temporally and spatially modulated spin structure that may stimulate intriguing spin-photon interactions as well as opto-spintronic applications. However, the development of such magnon-photon interface is hampered due to the lack of magnetic photonic structure that embraces strong light-matter interaction. Here, we present such magnon-photon interface in a CrSBr metasurface by showing the formation of a magnetic exciton polariton bound states in the continuum, whose energy and the radiative properties can be tuned with an external magnetic field. We further show that the exciton polaritons are modulated by the coherent magnon excitation, exhibiting a nontrivial magnon mode- and k-dependent behavior which suggests the formation of hybrid magnon-exciton polariton states. Our results shed light on the interplay of spin, magnon and photon in the magnetic metasurface and provide a new platform for exploring spin functional photonic and quantum devices. This work creates a magnon-photon interface from a 2D magnetic semiconductor metasurface. It demonstrates both the static and ultrafast control of exciton polaritons with spins and coherent magnons, paving the way for spin-based photonic devices.