Electric field dependent flux-flow resistance in the cuprate superconductor Nd2-xCexCuOy

This chapter is organized as follows: First we summarize the theoretical concepts dealing with the damping of the vortex motion, and we emphasize specifically the role played by the quasiparticle scattering. Then we briefly present the results of the flux-flow resistance measurements performed recently with NCCO at temperatures T<< Tc, demonstrating the highly nonlinear behaviour. Experimental results on the nucleation and growth of a high-electric-field domain are discussed in the following. The next section contains a general model discussion of the shifted nonequilibrium quasiparticle distribution and of the expected behaviour if this shift leads to an electric field dependence of the resistivity. In the following section we discuss our model based on the appearance of subbands between the Fermi energy and the gap energy. This model looks attractive if s-wave symmetry of the pair wave function prevails in NCCO. Thereafter we investigate another more general model in which a pronounced (step-like) structure in the energy dependence of the quasiparticle DOS between the Fermi energy and the gap energy is assumed. This second model looks more attractive in the case of d-wave symmetry of the pair wave function in NCCO. The final section contains the summary and conclusions. (orig.)