Simulated phase diagram of high-T-c vortex systems with point pins

In order to study effects of point pins in high-T-c vortex systems, randoml y-distributed plaquettes with weak interactions are introduced to the three -dimensional frustrated XY model. Simulated results are consistent with the oretical predictions and experiments. That is, the first-order flux-line me lting transition occurs in small density of point pins (the vortex liquid-B ragg glass transition), and the second-order glass transition takes place i n large density of point pins (the vortex liquid-vortex glass transition). In the Bragg glass phase, the structure factor shows a triangular Bragg pat tern and the percentage of entangled Box lines is very small, while these q uantities in the vortex glass phase are not different from those in the vor tex liquid phase.