Theory of the quasiparticle spectra around a vortex in the two-dimensional t-t′-J model

The local density of states around a vortex core, which can be observed in scanning tunneling spectroscopy, is studied in the two-dimensional t-J model and t-t'-J model in order to clarify the effect of correlation. The spatial dependence of the order parameter is numerically determined self-consistently under a uniform magnetic field using the Gutzwiller approximation. It is found that an s-wave component is locally induced around the core in the low-doping region, which leads to a splitting of the zero-energy peak in the local density of states near the core center. This may explain the scanning tunneling spectroscopy experiment in YBa2Cu3O7-delta. (C) 1998 Elsevier Science Ltd. All rights reserved.