The Ginzburg-Landau expansion and the slope of the upper critical field in disordered superconductors

It is shown that the slope of the upper critical field \dH(c2)/dT\(Tc) in superconductors with d pairing drops rapidly with increasing concentration of normal impurities, while in superconductors with anisotropic s pairing \dH(c2)/dT\(Tc) increases and reaches the well-known asymptotic level characteristic for the isotropic case. This difference makes it possible, in principle, to employ measurements of Hz in disordered superconductors as an experimental method for determining the type of pairing in high-T-c superconductors and systems with heavy fermions. (C) 1996 American Institute of Physics.