Pairing properties of the t -t'-t″-J model

We study the pairing properties of the two-dimensional t -t^'-t^″-J model, where t^' and t^″ are second and third neighbor hoppings, at a doping level x ≈0.1 . Recent studies of the t -t^'-J model find strong pairing for t^'>0 , associated with electron doping, but an absence of pairing for t^'<0 , associated with hole doping. This is in contrast to the cuprates, where the highest transition temperatures appear for hole doping. Model parametrizations for the cuprates estimate a t^″ comparable to t^', which, in principle, might fix this discrepancy. However, we find that it does not; we observe a suppression of pairing for the hole-doped system (t^'<0 ,t^″>0 ) , while for the electron-doped system (t^'>0 ,t^″<0 ) d -wave pairing is robust. Extended hoppings appear to be insufficient to make the one-band t -t^'-J model capable of describing the pairing in the hole-doped system.