Phase diagram of high-Tcsuperconductors: Influence of anisotropy and disorder

Abstract

We propose a phase diagram for the vortex structure of high-temperature superconductors which incorporates the effects of anisotropy and disorder. It is based on numerical simulations using the three-dimensional Josephson-junction array model. We support the results with an estimation of the internal energy and configurational entropy of the system. Our results give a unified picture of the behavior of the vortex lattice, from the very anisotropic ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8}$ to the less anisotropic ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$, and from the first-order melting ocurring in clean samples to the continuous transitions observed in samples with defects.