Quasiparticle resonant states as a probe of short-range electronic structure and Andre\'ev coherence
The recently observed properties of quasiparticle resonant states near impurities on the surface of superconducting BSCCO demonstrate that in-plane Andreev processes are either absent or phase-incoherent. Analysis of the spectral and spatial details of the electronic structure near a Zn impurity also suggest an effective magnetic component of the impurity potential. Further experiments are proposed to clarify whether the effective moments of nearby impurities are correlated.