Effects of Strong Correlations and Disorder in d-Wave Superconductors

We use exact diagonalization techniques to study the interplay between strong correlations, superconductivity, and disorder in a model system. We study an extension of the t-J model by adding an infinite-range d-wave superconductivity inducing term and disorder. Our work shows that in the clean case the magnitude of the order parameter is surprisingly small for low-hole filling, thus implying that mean-field theories might be least accurate in that important regime. We demonstrate that substantial disorder is required to destroy a d-wave superconducting state for low-hole doping. We provide the first bias free numerical results for the local density of states of a strongly correlated d-wave superconducting model, relevant for STM measurements at various fillings and disorders.