Generalized London theory of the mixed state of high-κ superconductors as a projection of the quasiclassical Eilenberger approach

The generalized London equation in the mixed state of high-kappa s-wave pairing superconductors with impurities is considered as a projection of the quasiclassical nonlocal nonlinear Eilenberger theory. Only one fitting parameter - the cutoff parameter xi(h) - is used in the theory. The distribution of the magnetic field is calculated self-consistently. Both nonlocal effects originated from extended states between the vortices and bound Andreev states in the vortex are taken into account. Comparison with different analytical nonlocal linear approaches (the Kogan-Gurevich, Amin-Franz-Affleck, Kogan-Zhelezina models) including only extended states is done. The importance of the Kramer-Pesch nonlinear effect and the field dependence of the cutoff parameter is emphasized and their strong influence on the variance of the magnetic field is found. The influence of the impurities on the ratio of the cutoff parameter xi(h) and the Ginzburg-Landau coherence length xi(c2) is considered. Quasiparticle scattering by impurities and lowering of the temperature reduces the value of xi(h) to the values much less than xi(c2). This is different from the prediction of the local Ginzburg-Landau theory where xi(h) is scaled by xi(c2). It is found that impurities influence by different way on the cutoff parameter xi(h) and the order parameter coherence length xi(1). The xi(h) decreases monotonously with the impurity scattering time in contrast to the nonmonotonous behavior of xi(1). The results can be used for analysis of the mu SR experimental data. (C) 2012 Elsevier B. V. All rights reserved.