Surface-Plasmon-Mediated Reduction in the Effective Gilbert Damping in Hybrid Photomagnetic Au/YIG:Co Bilayers

We demonstrate surface plasmon-mediated control of the magnetic damping in photomagnetic Co-doped yittrium iron garnet (YIG:Co)/Au bilayers. Tuning the excitation wavelength across the surface plasmon resonance at the Au/YIG:Co interface, we observe a twofold increase of the lifetime of the magnetization precession induced by the nonthermal photomagnetic effect in YIG:Co. The damping modulation is attributed to the plasmon-mediated spin Seebeck effect. Numerical simulations corroborate this mechanism and enable further exploration of the parameter space of the Au plasmonic system. We analyze the role of the Au grating thickness and discuss the range of thicknesses where the largest spin-Seebeck-driven reduction of magnetic damping can be accompanied by strong photomagnetic excitation. These results expand our understanding of the nanophotonic methods for controlling spin dynamics in ferrimagnetic media which are promising for future applications in information recording and data storage.