Superfluid density, condensation, and phase separation in high-T-c and other exotic superconductors

The universal correlations between T-c and the superfluid density n(s)/m* i n high-T-c superconductors (HTSC) are applicable also to systems with Zn-do ping, overdoping, and static magnetic stripe ordering. These three cases in volve microscopic phase separation, where n(s)/m* is proportional to the vo lume fraction of the superconducting region. T-c is determined predominantl y by n(s)/m* in a way similar to bulk and/or thin-film superfluid He-4 in o rdinary and porous media. The importance of 3-dimensional interlayer coupli ng in HTSC systems argues for the relevance of Bose-Einstein condensation o ver a simple Kosterlitz-Thouless transition. The intercalated HfNCl-Li-THF system (T-c = 25.5 K) shares energy-scale relations with HTSC and organic B EDT superconductors, following the universal correlations.