Effects of Point Defects on the Phase Diagram of Vortex States in High- Tc Superconductors in the B || c Axis

The phase diagram for the vortex states of high- T_c superconductors with point defects in the B-->∥c axis is drawn by large-scale Monte Carlo simulations. The vortex slush (VS) phase is found between the vortex glass (VG) and vortex liquid (VL) phases. The first-order transition between this novel normal phase and the VL phase is characterized by a sharp jump of the density of dislocations. The first-order transition between the Bragg glass (BG) and VG or VS phases is also clarified. These two transitions are compared with the melting transition between the BG and VL phases.