Magnetic resistivity and electron-magnon scattering in 3d ferromagnets

We determine the collective spin excitations and their contribution to the intrinsic resistivity in 3d ferromagnets by high field magnetotransport experiments. Well above the technical saturation of the magnetization, in the single domain magnetic state, the longitudinal magnetoresistance has a nonsaturating negative slope of about 0.02-0.05 muOmega cm T-1 at 300 K for Fe, Co, and Ni. We demonstrate its magnetic origin and assign the effect to a decrease of the electron-magnon scattering due to the damping of spin waves in high field. A convincing agreement is found between the high field measurements and our theoretical calculation of the spin flip electron-magnon scattering. This provides a unique estimate of the pure magnetic resistivity in 3d ferromagnets. (C) 2002 American Institute of Physics.