2-PHASE REGION OF VORTEX-SOLID MELTING - 3D XY THEORY

In clean enough samples of the high-T-c oxide materials, the phase tra nsition into the superconducting state occurs along a first-order line in the H-T plane. This means that a two-phase region occurs in the B- T plane, in which the liquid and solid vortex phases coexist. We discu ss the thermodynamics of this two-phase region, developing formulae re lating experimental quantities of interest. We then apply the 3D XY sc aling theory to the problem, obtaining detailed predictions for the bo undaries of the coexistence region. By using published data, we are ab le to predict the width of the two-phase region, and determine the phy sical parameters involved in the 3D XY description.