Origins of the damping in perpendicular media: Three component ferromagnetic resonance linewidth in Co–Cr–Pt alloy films

The 9.41GHz ferromagnetic resonance field and linewidth have been measured as a function of the angle (θH) between the external magnetic field and film normal for a series of 17.5nm thick Co–Cr–Pt alloy films. The linewidths ranged from hundreds of Oersted to kiloersted, with different values at θH=0 and θH=90° and additional minima and maxima for θH-values from 16° to 64°. The profiles can be fitted with a combination of inhomogeneity line broadening, grain boundary two magnon scattering, and magnon-electron (m-e) scattering processes, with a notably small Gilbert damping α-value of 0.004 for the m-e term.