Cooper-like Pairing and Energy Gap Induced by Ion Electronic Polarizability

We explore the possibility that the ionic electron polarizabilities of the oxygen ions in the cuprates and bismutates and the polarizabilities of As and Se ions in the iron pnictides contribute to charge carrier pairing leading to high Tc superconductivity. Using the fact that the ionic polarization responds to an abrupt change in the electric field is practically instantaneous, we find that charge carriers attract each other in limited regions in the two carrier position space. The attractive potential is used to calculate quantum mechanically the Cooper-like pairing energy and wave function and the gap energy showing they are consistent with pairing and gap energies of high Tc superconductors. Qualitative considerations show that this model may explain the large pairing energy observed in high Tc superconductors, the very short inter-carrier distance, the fact that Tc vanishes at very low and very high doping levels, and the dramatic increase in Tc of a one-unit cell thick FeSe film grown on SrTiO₃ substrate.