Determining The Gilbert Damping In Perpendicularly Magnetized Pt/Co/Alox Films

The Gilbert damping in perpendicularly magnetized Pt/Co/AlOx films is studied by means of the time-resolved magneto-optical Kerr effect. The Gilbert damping constant is observed to depend strongly on the AlOx layer thickness and the applied magnetic field. The magnetic field dependence is explained by extrinsic contributions to the damping due to inhomogeinities in the thin films. The intrinsic Gilbert damping is found to vary between 0.11 and 0.28 as a function of the AlOx thickness, which can be attributed to spin pumping from Co into the adjacent Pt film. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794538]