The Landau-Lifshitz-Gilbert damping parameter is typically assumed to be a local quantity, independent of the magnetic configuration. To test the validity of this assumption we calculate the precession damping rate of small amplitude non-uniform mode magnons in iron, cobalt, and nickel. At scattering rates expected near and above room temperature, little change in the damping rate is found as the magnon wavelength is decreased from infinite to a length shorter than features probed in recent experiments. This result indicates that the presence of weakly non-uniform modes, expected in real devices, should not appreciably affect the dynamic response of the element at typical operating temperatures. Conversely, at scattering rates expected in very pure samples around cryogenic temperatures, an order of magnitude decrease in damping rates is obtained for magnons with wavelengths commensurate with domain wall widths. While this low temperature result is likely of little practical importance, it provides an experimentally testable prediction of the non-local contribution of the spin-orbit torque-correlation model of precession damping. None of these results exhibit strong dependence on the magnon propagation direction.
Citation: Physical Review B (Condensed Matter and Materials Physics)
Pub Type: Journals
magnetization damping, spin wave, magnon, Landau-Lifshitz, Gilbert