Local quasiparticle states near a Zn impurity with induced magnetic moment in a high-T_c superconductor

The local quasiparticle density of states around a very strong nonmagnetic impurity with a Kondo-like magnetic moment induced at its nearest neighbors in a d-wave superconductor is studied. We show that the interference between the strong impurity potential scattering and the Kondo effect leads to novel quasiparticle spectra around the impurity, which are strikingly different from the case of a single unitary or magnetic impurity. The recent STM image of the local differential tunneling conductance around the Zn impurity in a high-T_c cuprate can be explained if the blocking effect of BiO surface layer between the tip and probed CuO₂ plane is taken into account.