Fe-content influence on the lattice dynamics and electron-phonon coupling of Mn_1-xFe_xSi

We have studied the lattice dynamics and electron-phonon (e-ph) coupling properties of the Mn_1-xFe_xSi alloy as a function of Fe-content. This system have been analyzed within the framework of density functional perturbation theory, using a mixed-basis pseudopotential method and the virtual crystal approximation (VCA) for modeling the alloy. In particular, the phonon dispersion as well as the phonon linewidth (γ), and the electron-phonon coupling (λ) have been calculated and analyzed with and without the inclusion of spin polarization. The observed evolution of particular phonon modes as a function of Fe-content is highly dependent of the spin-polarization, indicating the existence of a correlation between the spin ordering and the lattice dynamics. Such correlation is easily observed from the behavior of phonon linewidths and the electron-phonon coupling, and is discussed in terms of the interplay of electronic and vibrational properties of the alloy.