Spin resonance in AFe2Se2 with s-wave paring symmetry
We study spin resonance in the superconducting state of recently discovered alkali-intercalated iron selenide materials A_xFe_(2-y)Se_2 (A=K,Rb,Cs) in which Fermi surface has only electron pockets. We demonstrate that the hybridization-induced sign-changing unconventional s{+-}-wave symmetry, where the SC gap changes its sign between the hybridized pockets, support spin resonance, and the dynamical structure factor is consistent with the results of inelastic neutron scattering.