Entropic Weight in Cuprates: Is the Superfluid Depleted with Overdoping?

It is widely believed that cuprates (i) must be strong-coupling superconductors, (ii) their superconducting phase curve is governed by phase fluctuations, and (iii) exhibit a loss of superfluid density with increasing overdoping, hand-in-hand with the fall in Tc. Here we examine these issues for several canonical cuprates in the light of their electronic specific heat. We find evidence for near-weak-coupling behaviour where the mean-field Tc is governed by the gap amplitude, and fluctuations in both amplitude and phase serve only to partially diminish Tc from this mean-field value. We also find that, over the doping range considered, the superfluid density is not depleted with overdoping. As such, this work questions several prevailing paradigms in cuprate physics [1].