Spin dynamics in patterned nanometer-thick yttrium iron garnet films*

We present experimental investigations on the propagation of spin-wave modes in micro-structured yttrium iron garnet (YIG) stripes.$^{\mathrm{1}}$ The stripes were patterned by photo-lithography from high-quality 40-nm-thick YIG films grown by sputtering.$^{\mathrm{2}}$ Magnetization dynamics is driven by the rf field of a shorted coplanar waveguide patterned onto the YIG stripes. The propagation of spin waves are detected by means of spatially-resolved Brillouin light scattering microscopy. The propagation distance of spin waves is determined in the linear regime, where an exponential decay of 10 $\mu $m is observed. The estimated Gilbert damping parameter extracted from the spin-wave decay length is 3 times larger than that obtained through ferromagnetic resonance measurements in unstructured films, which is possibly due to enhanced two-magnon scattering in the patterned films. Furthermore, studies on the spin dynamics driven by spin-torque ferromagnetic resonance in YIG/Pt bilayers and the corresponding spatially-resolved spin-wave distribution are presented. $^{\mathrm{1}}$M. B. Jungfleisch, \textit{et al}., J. Appl. Phys., in press. $^{\mathrm{2}}$H. Chang, \textit{et al}., IEEE Magn. Lett. \textbf{5}, 6700104 (2014).