Flux-flow resistance in the cuprate superconductor Nd2-xCexCuOy: subbands,Bloch oscillations, and Zener breakdown

At intermediate magnetic fields B-c1 much less than B < B-c2 and at tempera tures T much less than T-c, the flux-flow resistance of the cuprate superco nductor Nd2-xCexCuOy (NCCO) displays two intrinsic steps as a function of t he electric field. In explaining this strongly nonlinear behavior, we propo se a scenario based on two subbands between the Fermi energy and the gap en ergy, leading to Bloch oscillations and Zener breakdown for the quasipartic le dynamics. The subbands originate from the Andreev bound states in the co re of an isolated vortex due to the interaction between the vortices. The p roposed scenario appears to explain in particular the observed magnetic fie ld and temperature dependence of the flux-flow resistance steps. (C) 2000 E lsevier Science B.V. All rights reserved.