Sharply vanishing destructive interference induced by magnon Kerr effect in cavity magnon polaritons

Motivated by the recently discovered nonlinear dynamics of cavity–magnon polaritons (CMPs), bistable CMP behavior is investigated theoretically in the case of two yttrium iron garnet (YIG) spheres (YIG1 and YIG2) in a microwave cavity, which is induced by the magnon Kerr effect of YIG1 originating from the magnetocrystalline anisotropy. The bistability appears in the form of sharp CMP frequency switching. More importantly, when the driving field acts on YIG1 and drives the magnon dark mode, the nonlinear Kerr effect at high excitation plays an important role in creating frequency detuning between the two YIG spheres. This results in sharply vanishing destructive interference between two YIG spheres and simultaneously makes the invisible magnon dark mode visible. However, when the driving field acts on the cavity, the magnon dark mode remains dark and there is no bistability in the CMPs when the driving frequency is tuned to the magnon dark mode, this being because the excitation energy cannot be transferred from cavity to magnon. The present research provides a promising approach for information storage and processing in multimode systems under high excitation.