Heavy-anion solvation of polarity fluctuations in pnictides

Once again the world of condensed matter has been surprised by the discovery of yet another class of high-temperature superconductors. The first reactions would of course be that these iron-pnictide- and iron-chalcogenide-based materials must in some way be related to the copper-oxide-based superconductors for which a large number of theories exist although a general consensus regarding the correct theory has not yet been reached. Here, we point out that the basic physical paradigm of the new iron-based superconductors is entirely different from the cuprates. Their fundamental properties, structural and electronic, are dominated by the exceptionally large pnictide electronic polarizabilities.