Non-local damping effects in Py-Cu-FeMn trilayers

We report a non-local enhancement of the Gilbert damping in Py-Cu-FeMn trilayers for in-plane ferromagnetic resonance measurements. We observe a 1/t dependence, t being the thickness of the permalloy, of the slope of the linewidth vs. frequency measurements indicating non-local contributions to the damping. In view of experimental verification of the adiabatic spin pump theory [1] in ferromagnetic heterostructures [2], these results suggest parallels in exchange biased systems. With the thickness of the non-magnetic layer, Cu, fixed below its spin-diffusion length, we understand this effect to be non-local resulting from the injection of spins by the precessing magnetization at the Py-Cu interface and subsequent scattering at the Cu-FeMn interface. \newline [1] Tserkovnyak et al., Rev. Mod. Phys. \textbf{77}, 1375 (2005). \newline [2] Heinrich et al. Phys. Rev. Lett. \textbf{90}, 187601 (2003)