  High temperature superconducting materials have been known since the
pioneering work of Bednorz and Mueller in 1986. While the microscopic mechanism
responsible for high Tc superconductivity is still debated, most materials
showing high Tc contain highly electronic polarizable ions, suggesting that the
mechanism driving high Tc superconductivity can be related to the ion
electronic polarizability in high Tc materials. Here we show that a free charge
carrier polarizes the ions surrounding it and the total electrical potential
generated by the charge carrier itself and the polarized ions becomes
attractive in some regions of space. Our results on bulk FeSe, monolayer FeSe
on SrTiO3 and La2CuO4 are in excellent agreement with the experiments. The fact
that the electronic polarizability explains correctly and quantitatively the
superconductivity parameters: Tc, gap and paring energies of both pnictides and
cuprates with similar polarizability parameters, suggests that the same model
may be applicable to other material systems within these groups as well as
other high Tc groups.
