Spin and Orbital Characters of Excitations in Iron Arsenide   Superconductors Revealed by Simulated Fe L-Edge RIXS
  We theoretically examine the orbital excitations coupled to the spin degree of freedom in the parent state of the iron-arsenide superconductor, based on the calculation in a five-band itinerant model. The calculated Fe $L_3$-edge resonant inelastic x-ray scattering (RIXS) spectra disclose the presence of spin-flip excitations involving several specific orbitals. Magnon excitations predominantly composed of a single orbital component can be seen in experiments, although its spectral weight is smaller than spin-flipped interorbital high-energy excitations. The detailed polarization and momentum dependence is also discussed with predictions for the experiments. 
E. Kaneshita, K. Tsutsui, and T. Tohyama
cond-mat.str-el cond-mat.supr-con