Enhanced sideband responses in a PT-symmetric-like cavity magnomechanical system

Based on the cavity magnomechanical system, which consists of a microwave cavity and a small ferromagnetic sphere, we propose a scheme to construct a parity-time- (PT-) symmetric-like system formed by the active magnon mode and passive cavity mode. The effective gain of the magnon mode is achieved by resonantly driving the yttrium iron garnet (YIG) sphere and can be modulated by the power of the driving field. We show the PT-symmetric phase transition following the variation of magnon-photon coupling strength in microwave regime. We find that the transmission amplitudes and time delays on the first- and second-order sidebands in the PT-symmetric-like system can be enhanced for three to four orders, compared to the magnomechanical system, once the magnon-photon coupling strength is tuned to the critical point in the broken-PT-symmetry regime. Particularly, we also show the switching between different transmission spectra (amplification or magnomechanically induced absorption) and time delay (positive or negative) on the first-order Stokes sideband can be achieved by modulating the power of the control field, cavity-waveguide coupling parameter, and magnon-photon coupling strength. Our study shows that the cavity magnomechanical system is a promising platform for exploring PT-symmetric-like paradigms in microwave field, and a good candidate for the microwave control on both the first- and high-order sidebands simultaneously. Our study may inspire further applications in frequency combs and low-power magnomechanical amplifier.