Ferromagnetic resonance linewidth in CoNi/FeMn bilayers

Out-of-plane ferromagnetic resonance (FMR) spectra of sputtered Co40Ni60/FeMn bilayers with various CoNi layer thicknesses were measured and analyzed by the Landau-Lifshitz-Gilbert equation. With increasing CoNi layer thickness, the effective demagnetizing field increases and the Lande g factor decreases. At the same time, the peak-to-peak linewidth DeltaH(pp) in the parallel and perpendicular configurations decreases. The angular dependence of the FMR linewidth can be described very well by the intrinsic Gilbert damping effect and the magnetic inhomogeneity. The Gilbert damping G factor is inversely proportional to the CoNi layer thickness and proportional to (g - 2)(2) with the variation of the CoNi layer thickness.