Effects of carrier concentration on the superfluid density of high-T_c cuprates

TL;DR

This study measures how the superfluid density in high-T_c cuprates varies with carrier concentration, revealing systematic changes linked to doping and potential connections to the energy gap.

Contribution

It provides detailed measurements of in-plane magnetic penetration depth across different doping levels in high-T_c cuprates, highlighting the relationship between superfluid density and carrier concentration.

Findings

Superfluid density varies systematically with doping.

$ ho_s(0)$ correlates with low energy spectral weight.

Initial slope of $ ho_s(T)$ increases with carrier concentration.

Abstract

The absolute values and temperature, T, dependence of the in-plane magnetic penetration depth, $\lambda_{ab}$, of La_{2-x}Sr_xCuO_4 and HgBa_2CuO_{4+\delta} have been measured as a function of carrier concentration. We find that the superfluid density, $\rho_s$, changes substantially and systematically with doping. The values of $\rho_{s}(0)$ are closely linked to the available low energy spectral weight as determined by the electronic entropy just above T_c and the initial slope of $\rho_{s}(T)/\rho_{s}(0)$ increases rapidly with carrier concentration. The results are discussed in the context of a possible relationship between $\rho_s$ and the normal-state (or pseudo) energy gap.