Temperature dependence of the resistivity in amorphous ferromagnetic alloys: Spin-wave contribution and resistivity minimum

The resistivities in amorphous ferromagnetic alloys of NicAu_1-c,CocAu_1-c and FecAu_1-c are measured as a function of temperature. The amorphous alloys are purely metallic and obtained by quenched condensation. The resistivity shows a T² temperature dependence which is due to electron-magnon interaction. From a theroretical point of view, the temperature dependence of the resistivity in amorphous metals provides an interesting problem because the lifetime of the conduction electrons is much shorter than the oscillation period of the magnons and phonons. Therefore, the elastic and inelastic scattering processes cannot be treated independently and the Ziman-Baym formula fails. Only exceptionally in Fe-rich FecAu_1-c alloys ($c>0.9$) we found the strong increase of the resistivity towards low temperature which has been observed by others in metallic glasses. This behavior is correlated with the sudden drop of the magnetic moment of the Fe atoms in this concentration region.