Revealing the dual nature of magnetism in iron pnictides and iron   chalcogenides using x-ray emission spectroscopy
  We report Fe K beta x-ray emission spectroscopy study of local magnetic moments in various iron based superconductors in their paramagnetic phases. Local magnetic moments are found in all samples studied: PrFeAsO, Ba(Fe,Co)2As2, LiFeAs, Fe1+x(Te,Se), and A2Fe4Se5 (A=K, Rb, and Cs). The moment size varies significantly across different families. Specifically, all iron pnictides samples have local moments of about 1 $\mu_B$/Fe, while FeTe and K2Fe4Se5 families have much larger local moments of ~2$\mu_B$/Fe, ~3.3$\mu_B$/Fe, respectively. In addition, we find that neither carrier doping nor temperature change affects the local moment size. 
H. Gretarsson, A. Lupascu, Jungho Kim, D. Casa, T. Gog, W. Wu, S. R.   Julian, Z. J. Xu, J. S. Wen, G. D. Gu, R. H. Yuan, Z....
cond-mat.supr-con cond-mat.str-el