Electron-magnon scattering and magnetic resistivity in 3d ferromagnets -: art. no. 024433

The determination of collective spin excitations and their contribution to the intrinsic resistivity via spin-flip electronic scattering are addressed for 3d ferromagnets using magnetotransport experiments. We present longitudinal high-field magnetoresistance (MR) measurements from 4 to 500 K and up to 40 T on Fe-, Co-, and Ni-patterned thin films. Well above the technical saturation of the magnetization-i.e., in the paraprocess regime-we report an almost linear and nonsaturating negative MR of around 0.01-0.03 muOmega cm T-1 at 300 K for the three magnets. We demonstrate its magnetic origin, and we assign this high-field resistivity decrease to the electron-magnon scattering and the spin-wave damping in high fields. We propose a theoretical calculation of the magnetic resistivity originating from spin-flip intraband s-s and d-d and interband s-d transitions via electron-magnon diffusion including both the high-field effect on the magnon spectrum and the magnon mass renormalization. Convincing agreements between the high-field measurements and our model provide a unique estimate of the pure magnetic resistivity in 3d ferromagnets. Our analysis also gives an insight into the low-energy spin waves-i.e., the theoretical magnon saturation field and the magnon mass renormalization consistent with neutron scattering results for the three magnets.