Dynamical regimes of vortex flow in type-II superconductors with parallel twin boundaries

Abstract

We explore the dynamics of driven magnetic flux lines in disordered type-II superconductors in the presence of twin boundaries oriented parallel to the direction of the applied magnetic field, using a three-dimensional elastic line model simulated with Langevin molecular dynamics. The lines are driven perpendicular to the planes to model the effect of an electric current applied parallel to the planes and perpendicular to the magnetic field. A study of the long-time non-equilibrium steady states for varying sample orientation and thickness reveals a rich collection of dynamical regimes spanning the depinning crossover region that separates the pinned and moving-lattice states of vortex matter. We observe the emergence of a preferred direction for the ordering of the Abrikosov lattice in the free-flowing vortex regime due to asymmetric pinning by the planar defects. We have performed novel direct measurements of flux line excitations such as half-loops and double kinks to aid the characterization of the topologically rich flux flow profile.

Barrier or easy-flow channel: The role of grain boundary acting on vortex motion in type-II superconductors*

“…As charge carriers, all the vortices are subjected to an additional electric force when they move into the specific area to model the GB as a potential well showing that the GBs are anisotropic pinning centers. [27][28][29] The direction of the electric force that the vortices subjected to in the local electric field is perpendicular to the GB and always points to inside of the GB region since the local electric fields on both sides of the GB equal in magnitude (due to quantities of twin boundaries existing in the cuprate superconductors) but opposite in direction.…”

Critical scaling and aging near the flux-line-depinning transition

“…In this present work, we employ an elastic line model to study critical behavior near the depinning transition for vortices in the presence of weak attractive random quenched disorder (point defects) in a three-dimensional system (d = 3) with a two-dimensional displacement vector (N = 2) [42][43][44][45][46][47] . We perform finite-temperature scaling on both steady-state velocity and radius of gyration data and thereby obtain the stationary critical scaling exponents β, δ, and ν that characterize the depinning process as a continuous second-order phase transition at zero temperature, finding β to be in good agreement with experimental values.…”