STRUCTURES OF SINGLE VORTEX AND VORTEX LATTICE IN A D-WAVE SUPERCONDUCTOR

The structures of a single vortex and vortex lattice in a superconduct or with d(x2-y2) symmetry are studied self-consistently employing a re cently developed Ginzburg-Landau theory. Near a single vortex, we foun d that an s-wave component of the order parameter is always induced, a nd it causes the local magnetic-field distribution and the d-wave orde r parameter to have a fourfold anisotropy. It is shown that there is a strong correlation between the structure of a single vortex and the s hape of the vortex lattice. Our numerical calculation indicates that t he structure of the vortex lattice is always oblique except for temper atures very close to T-c where it becomes triangular. The possible con nection of the result with experiment is also discussed.