Lindemann criterion and vortex-matter phase transitions in high-temperature superconductors

The vortex-matter in superconductors is generally believed to exist in two main phases, vortex-solid and vortex-liquid. Recent investigations of the phase diagram of anisotropic high-temperature superconductors indicate, however, the existence of at least three distinct phases: relatively ordered quasi-lattice, highly-disordered entangled vortex-solid, and a liquid phase. A theoretical analysis in terms of an extended Lindemann criterion provides a quantitative description of the resulting vortex-matter phase boundaries and the behavior of the transition lines with varying anisotropy and disorder. (C) 1998 Elsevier Science B.V.