PAIRING ANISOTROPY AND MACROSCOPIC ANISOTROPY OF SUPERCONDUCTORS

Macroscopic properties of the superconductivity are investigated in the tight-binding picture taking account of the intersite pairing as well as the on-site pairing. We discuss the case of a layered material, a cubic material, and a quasi-one-dimensional material. A multicomponent Ginzburg-Landau equation, which takes the intersite-pairing effect into account as the different components of the order parameter, is derived from a microscopic theory. The angle dependence of the upper-critical field Hc2 is analyzed based on that equation and how the intersite interactions affect the anisotropy of Hc2 is clarified. The Fermi-energy dependence of the transition temperature Tc, which does not simply reflect the density of states, is also discussed. © 1990 The American Physical Society.