Possible superconductivity mechanism in high-temperature superconductors

The formation temperature (T*~ 135 K) is determined in the Shubin-Vonsovski approximation for local electron pairs in the CuO₂ planes of YBa₂Cu₃O₇ crystal. This estimate is used to obtain the Coulomb pseudopotential µ*≈?0.15. In the presence of strong electron-phonon coupling (λ ~0.5) and electron correlation in the electron pairing, the estimate of critical temperature T _c ≈99 K agrees, by the order of magnitude, with its experimental value. The calculated ratio 2Δ/kT _c ≈4.13 confirms the presence of strong electron pairing.