Cooper-like Pairing and Energy Gap Induced by Ion Electronic Polarizability
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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.
KeywordsHigh Tc Superconductivity Polarizability Cuprates Pnictides
The authors gratefully acknowledge useful discussions with Dror Orgad from the Hebrew University of Jerusalem.
- 8.Hyungju, O h, Moon, Jisoo, et al.: Brief review on iron-based superconductors: are there clues for unconventional superconductivity? Progress Supercond. 13, 65 (2011)Google Scholar
- 12.Tinkam, M.: Introduction to superconductivity. Mc-Graw Hill (1995)Google Scholar
- 13.Abrikosov, A.A., Gor’kov, L.P., Dzyaloshinski, I.Y.: Quantum field theoretical methods in statistical physics, 2nd edn. Pergamon Press (1965)Google Scholar
- 16.Alexandrov, A.S.: Theory of high temperature superconductivity in cuprates and other doped polar insulators. J. Supercond. Nov. Magn. 1389 (2012)Google Scholar
- 18.Drechsler, S.L., Rosner, H., et al.: New insight into the physics of iron pnictides from optical and penetration depth data. arXiv:0904.0827
- 24.Berciu, M., Elfimov, I., Sawatzky, G.A.: Electronic polarons and bipolarons in iron-based superconductors: the role of anions. Phys. Rev. 214507, B79 (2009)Google Scholar
- 30.Wang, Q.Y., et al.: Interface-induced high-temperature superconductivity in single unit-cell FeSe films on SrTiO3. Chin. Phys. Lett 037402, 29 (2012)Google Scholar
- 33.Zhang, S., et al.: The role of SrTiO3 phonon penetrating into thin FeSe films in the enhancement of superconductivity arXiv:x1605-0694[V] (2016)