Dynamics of Dislocation Dipole Motion in the Flux Line Lattice of Type-II Superconductors

The motion of flux line dislocation (FLD) dipoles is shown to be a more important mechanism for flux transport than the motion of individual FLDs. The electric field generated by FLD dipoles moving at a terminal velocity v is $${\mathrm{E=(Bby}}_s\mathrm{)\Lambda v}$$ , where B is the magnetic induction, b is the magnitude of the Burgers vector, y_s is the separation between the individual FLDs in each dipole, and A is the density of moving FLD dipoles. The terminal velocity is found to be proportional to (J‐J_c), where J_c is a critical current density. The analogy between the above equation and the corresponding equation for the plastic‐shear strain rate in metals is explored in order to qualitatively explain yield phenomena and time‐dependent hysteresis in E‐J curves. Possible FLD dipole sources and the portion of experimental E‐J curves likely to be affected by FLD motion are also discussed.