Charge carrier dynamics and the critical vortex velocity in high-T_c superconductors

Abstract

A model is presented to explain the recently observed voltage jumps in Bi₂Sr₂CaCu₂O_8+δ superconducting thin films. The present approach provides additional evidence of the validity of the flux-flow instability model. The field and temperature dependences of the critical vortex velocity were attributed to the physics of the vortex core in clean superconductors (high-T _c superconductors) which is very different from the physics of the vortex core in dirty superconductors. The quasiparticle diffusion coefficient D _qp was calculated based on the assumption that the quasiparticle motion is considered as a transport phenomenon on random walks. In addition, the effects of scattering of normal excitations by quasiparticles localized in the vortex core moving together with the vortex on the inelastic scattering time of quasiparticles τ_in was also calculated. The predictions of the model and the experimental observations are in excellent agreement.