GINZBURG-LANDAU THEORY FOR D-WAVE PAIRING AND FOURFOLD SYMMETRICAL VORTEX CORE STRUCTURE

The Ginzburg Landau theory for d(x2-y2)-wave superconductors is constr ucted, by starting from the Gor'kov equation with including correction terms up to the next order of ln(T-c/T). Some of the non-local correc tion terms are found to break the cylindrical symmetry and lead to the fourfold symmetric core structure, reflecting the internal degree of freedom in the pair potential. Using this extended Ginzburg Landau the ory, we investigate the fourfold symmetric structure of the pair poten tial, current and magnetic held around an isolated single vortex, and clarify concretely how the vortex core structure deviates from the cyl indrical symmetry in the d(x2-y2)-wave superconductors.