The doping dependence of the superfluid density, r_s, of high-Tc superconductors is usually considered in the context of the Uemura relation, namely Tc proportional to rs, which is generally assumed to apply in the underdoped regime. We show that a modified plot of Tc/Do versus rs, where Do is the maximum d-wave gap at T=0, exhibits universal features that point to an alternative interpretation of the underlying physics. In the underdoped region this plot exhibits the canonical negative curvature expected when a ground-state correlation competes with superconductivity (SC) by opening up a gap in the normal-state DOS. In particular rs is suppressed much faster than Tc/Do or indeed Tc. The pseudogap is found to strongly modify the SC ground state.
@article{arxiv.cond-mat/0211071,
title = {The superfluid density in cuprate high-Tc superconductors - a new paradigm},
author = {J. L. Tallon and J. W. Loram and J. R. Cooper and C. Panagopoulos and C. Bernhard},
journal= {arXiv preprint arXiv:cond-mat/0211071},
year = {2009}
}