Local antiferromagnetic correlations in the iron pnictide   superconductors LaFeAsO{1-x}F{x} and Ca(Fe,Co)2As2 as seen via normal-state   susceptibility
  We have studied the interplay of magnetism and superconductivity in LaFeAsO$_{1-x}$F$_x$ and Ca(Fe$_{1-x}$Co$_x$)$_2$As$_2$. While antiferromagnetic spin density wave formation is suppressed and superconductivity evolves, all samples show a doping independent strong increase of the normal state susceptibility upon heating which appears a general feature of iron pnictides. The data provide evidence for robust local antiferromagnetic correlations persisting even in the superconducting regime of the phase diagram. 
R. Klingeler, N. Leps, I. Hellmann, A. Popa, U. Stockert, C. Hess, V.   Kataev, H.-J. Grafe, F. Hammerath, G. Lang, G. Behr,...