Flux Flow ind-Wave Superconductors: Low Temperature Universality and Scaling

We demonstrate that superclean $d$-wave superconductors with ${\Delta }_{\infty }^2\tau /E_F\gg 1$ display a novel type of vortex dynamics: At low temperatures, both dissipative and transverse components of the flux-flow conductivity are found to approach universal values even in the limit of infinite relaxation time. A finite dissipation in the superclean limit is explained in terms of the Landau damping on zero-frequency vortex modes which appear due to minigap nodes in the bound-state spectrum in the vortex core. In the moderately clean regime the scaling law at low $T$ and low field is obtained.