Temperature Dependences of the Resistivity and the Ferromagnetic Resonance Linewidth in Permalloy Thin Films

The contribution of conduction electron scattering to magnon relaxation in Permalloy thin films [2-20 nm] was studied by resistivity measurements and by high frequency permeability measurements using network analyzer ferromagnetic resonance. Both effective Gilbert damping alpha of the magnetization and electrical resistivity rho were measured from room temperature down to 10 K. We observe that an increase of the resistivity does not necessarily lead to an increase of the effective damping. Indeed, increases up to 50% of the resistivity in the studied temperature range are not accompanied by any change of the damping parameter alpha. We discuss our findings by sorting out the different conduction electron scattering channels that lead to spin-flip, and that hence contribute to the overall damping. We conclude that alloy disorder scattering is the main channel that leads to correlated contributions to damping and resistivity