Local Quasiparticle States near a Unitary Impurity with Induced Magnetic Moment in a d-Wave Superconductor

Abstract

The local quasiparticle density of states around a unitary impurity with a Kondo-like magnetic moment induced at its nearest neighbors in a d-wave superconductor is studied within the slave-boson mean-field approach. The Hamiltonian is exactly diagonalized and the results are obtained self-consistently. 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 a Zn impurity in a high-T_c cuprate can be essentially explained if the blocking effect of BiO surface layer between the tip and probed CuO_2 plane [Zhu et al., Phys. Rev. B 62, 6207 (2000)] is taken into account.