On the nature of superconductivity in the t-J model of high-Tc superconductors

Using an extended dynamical cluster approximation we study superconductivity in the two-dimensional t-J model. In analogy to the extended dynamical mean field theory, non-local spin fluctuations are treated self-consistently with an additional Bosonic bath. To solve the effective cluster problem, we employ an extended non-crossing approximation which allows for transitions to the symmetry-broken state. At sufficiently low temperatures we find a stable superconducting solution with d-wave order parameter. Upon pairing, the exchange energy is lowered, consistent with an exchange-based pairing mechanism.