Magnetic properties in ultra-thin 3d transition metal alloys II: experimental verification of quantitative theories of damping and spin-
Martin A. Schoen, Juriaan Lucassen, Hans T. Nembach, Thomas J. Silva, Bert Koopmans, Christian Back, Justin M. Shaw
A systematic study of the Gilbert damping is performed via ferromagnetic resonance for the disordered crystalline binary 3d transition metal alloys NiCo, NiFe and CoFe over the whole range of alloy compositions. After accounting for the inhomogeneous linewidth, the measured damping shows clear evidence for the presence of additional extrinsic contributions, such as interfacial damping enhancement (by spin pumping) and radiative damping. We quantify these two extrinsic contributions and thus determine the intrinsic alloy damping. The comparison of the so determined intrinsic damping to multiple theoretical calculations13 yields in most cases good qualitative and quantitative agreement. Furthermore, the values of the damping obtained in this study are compared to a wide range of published experimental and theoretical values corroborating the validity of our results. Additionally, we find a concentration dependence of the spin mixing conductance in the alloy systems.