Quasiparticle states near surfaces of high-Tc superconductors based on the extended t-J model

Quasiparticle properties near surfaces of d-wave superconductors are numerically studied based on the extended t-J model with Gutzwiller approximation. In order to simulate detailed profiles of the local density of states, the amplitudes of the transfer integrals are chosen so as to reproduce the Fermi surfaces of high-T-c superconductors. It is shown that the spatial dependence of the local density of states is sensitive to the geometry of the surface, the shape of the Fermi surface, and the doping rate delta. In particular, clear delta dependences are obtained in spectral features, i.e., zero-energy peaks and their splitting due to the inducement of an s-wave component which breaks time-reversal symmetry. The present results suggest that the microscopic parameters of actual materials can be extracted from a detailed analysis of scanning tunneling spectroscopy data.