Generation of magnonic frequency combs in a <i>PT</i> -symmetric cavity magnomechanical system

Non-Hermitian magnonics, combining non-Hermitian physics and magnonics, has become a significant research topic in magnon spintronics. Here, we investigate the magnonic spectrum in a PT -symmetric cavity magnomechanical system. We find that magnonic frequency combs can be generated when the system is in the PT -symmetric phase. The magnonic frequency comb features an ultralow driving threshold in the blue-detuned regime. And the magnonic frequency comb can be generated in the red-detuned regime, which is difficult to implement in the passive magnomechanical systems. These new features come from the fact that the dissipation of two eigenmodes in the PT -symmetric phase is enormously reduced, which leads to the effective enhancement of the magnomechanical nonlinearity. This work provides a promising route for generating low-power magnonic frequency combs and offers the prospect of exploring PT -symmetric magnonic devices.