Phase transitions in a two-dimensional vortex system with defects: Monte carlo simulation

The phase states and phase transitions in a system consisting of a two-dime nsional vortex lattice with defects are studied by the Monte Carlo method. It is shown that a "rotating lattice" phase, which is an intermediate phase between the vortex crystal and vortex liquid phases, is present. The depen dence of the temperature of the transition from the rotating lattice phase into a vortex liquid on the strength of the defect potential is determined. The current-voltage characteristics of the system are calculated at variou s temperatures for point, square, and linear defects. It is shown that the phase state of the system strongly affects its transport properties. (C) 20 00 MAIK "Nauka/ Interperiodica".