VORTICES AND 2D BOSONS - A PATH-INTEGRAL MONTE-CARLO STUDY

The vortex system in a high-T-c superconductor has been studied numeri cally using the mapping;to 2D bosons and the path-integral Monte Carlo method. We find a single first-order transition from an Abrikosov lat tice to an entangled vortex liquid. The transition is characterized by an entropy jump Delta S approximate to 0.4k(B) per vortex and layer ( parameters for YBa2Cu3O7) and a Lindemann number c(L) approximate to 0 .25. The increase in density at melting is given by Delta rho approxim ate to 6.0 x 10(-4)/lambda(T)(2). The vortex liquid corresponds to a b osonic superfluid, with rho(s), = rho even in the limit lambda --> inf inity.