Impurity effects on quasiparticle c-axis planar tunneling and STM spectra in high-Tc cuprates

We present self-consistent calculations of the electronic structure near strongly scattering impurities in cuprate superconductors described by a realistic band structure and order parameter magnitude. Energies and highly asymmetric line shapes of resonances, changes in gap-edge features, and local changes in the order parameter are determined for magnetic and nonmagnetic potentials. Experimental tunneling spectra are well fitted by calculations using a d-wave order parameter. The local density of states near such impurities is also calculated.