Remarks on the Uemura plot for weakly interacting charged Bose fluids

Abstract

In the paper Enz and Galasiewicz [ Physica C 214 (1993) 239] one finds, for weakly repulsive Bose fluids the T c - n s relation which reproduces reasonably well the straight line part of “Uemura plot”. In the formula for superfluid density n s = n s( t 1, t ∼ 1) the integrals were presented as power series with respect to t 1 = t 1( t c) ⪡ 1, where dimensionless parameters t 1, t, t c describe interaction, temperature and critical temperature, respectively. Here, the integrals have been calculated numerically in a wider interval of parameters. Among new results we have found that, while for weak interaction t c > t c 0 ( t c 0 denotes critical temperature for free bosons), for the stronger one, like in superfluid helium 4, t c < t c 0. As concerns curves T c ( n s) we find that in the “straight line” part the slight bending upward is local and very soon begins a much faster descent, like on the Uemura plot for type II high- T c superconductors. The lowest experimental data for carrier densities n s and m ★ = 5 m e lead to λ L ∼ 1000 A ̊ , ξ ∼ 1 A ̊ , T c ∼ 360 K .