Resonant states in high-temperature superconductors with impurities

A microscopic theory of resonant states lot the Zn-doped CuO2 plane in the superconducting phase is formulated in the effective I-J model. In the model derived from the original p-d model, Zn impurities are considered as vacancies for the d states at Cu sites. In the superconducting phase, in addition to the local static perturbation induced by the vacancy, a dynamical perturbation appears that results in a frequency-dependent perturbation matrix. Using the T-matrix formalism for the Green's functions in terms of the Hubbard operators, we calculate the local density of electronic states with d, p, and s symmetries.