Collective magnetic excitations of C4-symmetric magnetic states in iron-based superconductors

We study the collective magnetic excitations of the recently discovered C-4-symmetric spin-density-wave states of iron-based superconductors with particular emphasis on their orbital character based on an itinerant multiorbital approach. This is important since the C-4-symmetric spin-density-wave states exist only at moderate interaction strengths where damping effects from a coupling to the continuum of particle-hole excitations strongly modify the shape of the excitation spectra compared to predictions based on a local moment picture. We uncover a distinct orbital polarization inherent to magnetic excitations in C-4-symmetric states, which provide a route to identify the different commensurate magnetic states appearing in the continuously updated phase diagram of the iron-pnictide family.