Study On The Melting Transition And Creep Motion Of Two-dimensional Vortex Lattice Using Computer Simulation

In the first four chapters of the thesis, we investigated melting transition and dynamic properties of 2D vortex lattice in the periodic square pinning array using molecular dynamics simulation. For the case that vortex number is equal to pinning number, we get the melting phase diagram at different pinning strength by annealing method. At zero temperature, we found triangular lattice structure for weak pinning and square lattice structure for strong one. Accordingly, we found two different phase transitions by investigating the temperature dependence of structure factor and energy. We also investigated the relationship between vortex motion and driving force at zero and finite temperatures. This gave us an intuitionistic knowledge of the pinning effect on vortices. In chapter 5, we simulated the dynamics in two-dimensional fully frustrated Coulomb gas model, and studied the law for creep motion at low electric field. We found that the energy barrier increases logarithmically with the decrease of the electric field. The results help us to understand the behaviour of many different physical systems, such as 2D JJAs, superconducting films, as well as high-Tc superconductors.