Nonlinear magnon polaritons

Abstract

We experimentally and theoretically demonstrate that nonlinear spin-wave interactions suppress the hybrid magnon-photon quasiparticle or "magnon polariton" in microwave spectra of an yttrium iron garnet film detected by an on-chip split-ring resonator. We observe a strong coupling between the Kittel magnon and microwave cavity mode in terms of an anti-crossing as a function of magnetic fields at low microwave input powers, but a complete closing of the anti-crossing gap at high powers. The experimental results are well explained by a theoretical model including the three-magnon decay of the Kittel magnon into spin waves. The gap closure originates from the saturation of the ferromagnetic resonance above the Suhl instability threshold by a coherent back reaction from the spin waves.

Significant suppression of two-magnon scattering in ultrathin Co by controlling the surface magnetic anisotropy at the Co/nonmagnet interfaces

“…Although it has been realized to provide tunability for the strong magnon-photon coupling system based on Ye 3 Fe 5 O (YIG) by controlling microwave power [14,15], to control the magnon-photon coupling state via electric modulation of a magnon is still a significant challenge, since its realization expands a border of an application of quantum coupling systems by means of conventional electronic approaches, such as that for field-effect transistors. Hence, magnon-photon coupling between magnons excited in ultrathin FM films and microwave photons can pave the way toward the realization of a gate-tunable magnon-photon coupling system.…”

“…However, the current obstacle to the application of magnon-photon coupling is low tunability. Indeed, there are some studies aiming to realize tunable magnon-photon coupling via modulation of photon excitation [14,15]. However, important to note is that direct control of a magnon state was demonstrated only via temperature control, where tuning of the coupling between magnons excited in gadolinium iron garnet and photons confined within a three-dimensional microwave cavity was realized [16].…”