Spin waves in micro-structured yttrium iron garnet nanometer-thick films

We investigated the spin-wave propagation in a micro-structured yttrium iron garnet waveguide of $40$ nm thickness. Utilizing spatially-resolved Brillouin light scattering microscopy, an exponential decay of the spin-wave amplitude of $(10.06\pm 0.83)$ $\mu$m was observed. This leads to an estimated Gilbert damping constant of $\alpha =(8.79\pm 0.73)\times {10}^{-4}$, which is larger than damping values obtained through ferromagnetic resonance measurements in unstructured films. The theoretically calculated spatial interference of waveguide modes was compared to the spin-wave pattern observed experimentally by means of Brillouin light scattering spectroscopy.