Cutoff parameter versus Ginzburg-Landau coherence length in the mixed state of high-κ superconductors with impurities: quasiclassical approach

The influence of the impurities on the ratio of the cutoff parameter, ξh and the Ginzburg-Landau coherence length, ξc2, in the mixed state of high-κ s-wave superconductors is investigated in framework of the quasiclassical nonlocal Eilenberger theory. Quasiparticle scattering by impurities and lowering of the temperature reduce the value of ξh to values much less than ξc2. This is different from the prediction of the local Ginzburg-Landau theory where ξh is scaled by ξc2. Detailed comparison with the behavior of the order parameter coherence length ξ1 is done. It is found that impurities influence by different way on ξh and ξ1. The curve ξh/ξc2(B/Bc2) shifts downward with increasing of impurity scattering rate while ξ1/ξc2(B/Bc2) curve shifts upward in this case.