The mechanism of anisotropic exchange interaction in superconducting   iron arsenides
  Using a combination of linear response theory and constrained orbital hybridization approach, we study the mechanism of magnetic exchange interaction of iron-based superconductor. We reproduce the observed highly anisotropic exchange interaction, and our constrain-orbital calculation unambiguously identifies that the anisotropic feature of exchange interaction is not sensitive to the unequal d$_{xz}$/d$_{yz}$ orbital population. 
Xiangang Wan, Jinming Dong, Xi Dai
cond-mat.supr-con cond-mat.mtrl-sci