Universal trends in extreme type-II superconductors

Experimental results of the muon-spin-relaxation rate, the pressure dependence coefficient and the isotope effect coefficient of the transition temperature of extreme type-II superconductors are analyzed in terms of an ansatz leading to a parabolic dependence of the transition temperature on condensate density. The resulting universal properties and trends are remarkably consistent with experiment and imply crucial constraints on the microscopic theory. © 1992 The American Physical Society.