EPL, 86 (2009) 17006
DOI: 10.1209/0295-5075/86/17006

Heavy-anion solvation of polarity fluctuations in pnictides

G. A. Sawatzky¹, I. S. Elfimov¹, J. van den Brink^{2, 3} and J. Zaanen<sup>2

1</sup>   Department of Physics and Astronomy, University of British Columbia - Vancouver, BC V6T-1Z1, Canada
²   Institute Lorentz for Theoretical Physics, Leiden University - P.O. Box 9506, 2300 RA Leiden, The Netherlands, EU
³   Institute for Molecules and Materials, Radboud Universiteit Nijmegen - P.O. Box 9010, 6500 GL Nijmegen, The Netherlands, EU

elfimov@phas.ubc.ca

received 16 January 2009; accepted in final form 15 March 2009; published April 2009
published online 22 April 2009

Abstract
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.

PACS
71.10.-w - Theories and models of many-electron systems.
74.20.-z - Theories and models of superconducting state.

© EPLA 2009