Magnetic relaxation of normal-metal (NM)/80NiFe/NM films

Ferromagnetic resonance was measured for Cu/80NiFe(Py)/Cu/Pt films with various thicknesses of Cu spacer (dCu) in order to clarify the mechanism of the enhancement of Gilbert damping parameter (G) for Pt/Py/Pt films reported previously. The peak-to-peak linewidth (ΔHPP) for the Cu/Py/Cu/Pt film was very large at dCu=0 A and decreased gradually with increasing dCu. The out-of-plane angular dependence of ΔHPP for Cu/Py/Cu/Pt films was measured and analyzed using Landau-Lifshitz-Gilbert equation, by taking into account the magnetic inhomogeneities. The value of G obtained from analysis of the Cu/Py/Cu/Pt film was about twice larger than that for Cu/Py/Cu film even at dCu=100 A and decreased gradually as dCu increased