From antiferromagnetism to d-wave superconductivity in the two-dimensional t-J model

We have found that the two dimensional t-J model, for the physical parameter range J/t= 0.4 reproduces the main experimental qualitative features of high-ir, copper oxide superconductors: d-wave superconducting correlations are strongly enhanced upon small doping and clear evidence of off-diagonal long-range order is found at the optimal doping delta approximate to 0.15. On the other hand, antiferromagnetic long-range order, clearly present at zero hole doping, is suppressed at small hole density with clear absence of antiferromagnetism at delta>-0.1.