Extreme type II superconductors: universal trends

Motivated by the Uemura plot, which relates the measured Tc to the zero temperature μSR relaxation rate [1-3], and by the hyperuniversal relation between Tc and critical amplitudes of the London penetration depth and phase correlation length [4-6], we propose a simple ''universal'' scaling ansatz, where the plot of the rescaled transition temperature versus rescaled μSR relaxation rate should fall on a single parabola. This scaling ansatz is remarkably consistent with the μSR data for a large class of cuprate and Chevrel-phase superconductors. In agreement with experiment, it also implies universal trends in the pressure (α) and isotope (β) coefficients. (orig.)