Effect of the spin-orbit coupling and impurity scattering on the spin resonance peak in three-orbital model for Fe-based superconductors

Here we study a combined effect of the spin-orbit coupling and scattering on the nonmagnetic disorder on the formation of the spin resonance peak in iron-based superconductors. Spin susceptibility is calculated within the random phase approximation. The spin resonance peak becomes broader with the increase of disorder and its frequency also shifts. At the same time, the spin response in the $s_\pm$ state is different from that of the $s_{++}$ state.