Electron-phonon coupling in ferromagnetic Fe-Co alloys from first principles

We calculate from first principles the electron-phonon coupling strength in ferromagnetic iron-cobalt Fe_1-xCo_x alloys for compositions ranging from x=0 to x=0.75. We find strong, spin-dependent variation of the electron-phonon coupling strength with alloy composition. The minimum of the electron-phonon interaction is found near the composition x=0.25. We analyze the variation of the electron-phonon interaction with composition, as a function of electron spin, density of states, electron-phonon matrix elements, and phonon frequencies. Our results are in good qualitative agreement with magnetization dynamics experiments.