Study of anisotropy on critical currents in type II superconducting films with hexagonal disorder at finite temperature.

Abstract

One of the most used mechanisms to increase the critical current in type II high critical temperature superconducting materials is the pinning of vortices. When a transport current J is applied and exceed a critical value Jc, the vortices move and dissipate energy. Several efforts have been made from the experimental point of view to increase the effect of pinning in this type of materials, creating structural defects using several techniques, mainly irradiation. However, the pinning mechanism is not fully understood yet, and has been object of theoretical research trying to understand its influence in both, the critical currents and dynamical behavior of the vortex system. The goal of the present work is to calculate the critical current of a vortex system submitted to a transport current with a periodical pinning network of hexagonal symmetry at finite temperature. The vortex system will be described by a set of Langevin equations and the trajectories and velocities will be obtained using the Molecular Dynamic technique. With the trajectories, we will be able to obtain the dynamical behavior of the vortex system, and the velocities will provide us the critical currents. The understanding of pinning mechanism is important because may help to discover new and more efficient superconducting materials, which is important for technological applications.