Multifunctional nonlinear planar device of cavity magnonics based on a 100 nm-thick YIG film

Abstract

The paper demonstrates a multifunctional nonlinear planar cavity magnonic device based on a coupled photon–magnon system “half-wave microstrip resonator–superthin (100 nm thick) yttrium iron garnet (YIG) film.” The microstrip resonator of 500 μm width (a photonic subsystem) operates at a resonant frequency of about 3 GHz, and the superthin YIG film (a magnonic subsystem), being a gyromagnetic resonator, operates in a parallel pumping mode at a resonant frequency that corresponds to a ferromagnetic resonance (FMR) frequency f⊥ for a transverse pumping mode. The FMR mode at f⊥ is excited in the regime of a strong coupling, and it is not excited when the microstrip resonator is replaced by a microstrip transmission line operating in the parallel pumping mode. At a second-order Suhl instability, a large-to-small signal ratio and a nonlinear phase shift reach the maximum values of about 8 dB and 60° when the resonant frequencies of both subsystems coincide. A frequency selectivity of the multifunctional nonlinear device is estimated in a two-signal (large and small signals) regime. The presence of a lower nonlinear threshold in superthin YIG films in comparison with micrometer-thick YIG films leads to the improvement of the frequency selectivity of the nonlinear ferrite devices.