Superconducting pairing of spin polarons in the t-J model

The pairing of quasiparticles in a CuO₂ plane is studied within a spin-polaron formulation of the t-t|IH-J model. Our numerical solution of the Eliashberg equations unambiguously shows d-wave pairing between spin polarons on different sublattices mediated by the exchange of spin fluctuations, and a strong doping dependence of the quasiparticle bandwidth. The transition temperature Tc is an increasing function of J/t and crosses a maximum at an optimal doping concentration δₒₚₜ. For the t-J model with J/t=0.4 we obtain Tc{}0.013t at δₒₚₜ{}0.2.