d-Wave Pairing in an Ensemble of Spin Polaron Quasiparticles in the   Spin-Fermion Model of the Electronic Structure of the CuO2 Plane
  It is demonstrated for the first time that the strong coupling between spin moments of copper ions and oxygen holes, which arises upon hybridazation mixing of two hole subsystems in the Emery model, not only affects the formation of spin polaron quasiparticles but also ensures effective attraction between them via the exchange interaction. This results in the Cooper instability with d-wave pairing in a 2D ensemble of spin polaron quasiparticles. The T-x-phase diagram obtained using this approach agrees well with the available experimental data. 
V.V. Val'kov, D.M. Dzebisashvili, A.F. Barabanov
cond-mat.supr-con cond-mat.str-el