1995/11/27 by Ji-Hai Xu, Yong Ren, Xu, Ji-Hai +3
Physics and Astronomy · #Condensed Matter (cond-mat) #FOS: Physical sciences #Physics of Superconductivity and Magnetism #Quantum Chromodynamics and Particle Interactions #cond-mat
paper · pdf · doi:10.48550/arxiv.cond-mat/9511130
16 pages, latex, 11 figures availabe on request
arxiv created 1995/11/27 · openalex publication_date 1995/11/27 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
YBa2Cu3O7 (YBCO) exhibits a large anisotropy between the a and b axes in the CuO2 planes because of the presence of CuO chains. In order to account for such an anisotropy we develop a Ginzburg-Landau (GL) theory for an anisotropic d-wave superconductor in an external magnetic field, based on an anisotropic effective mass approximation within CuO2 planes. The anisotropic parameter λ=mx/my, where mx (my) is the effective mass in the x (y) direction, is found to have significant physical consequences: In the bulk case, there exist both the s- and d-wave order parameters with the same transition temperature, as long as λ≠ 1. The GL equations are also solved both analytically and numerically for the vortex state, and it is shown that both the s- and d-wave components show a two-fold symmetry, in contrast to the four-fold symmetry around the vortex, as expected for the purely d-wave vortex. With the deviation of λ from unity, the opposite winding between the s- and d-wave components observed in the purely d-wave case is gradually taken over by the same winding number. The vortex lattice is found to have oblique structure in a wide temperature range with the precise shape depending on the anisotropy.