Finite temperature superfluid density in very underdoped cuprates

TL;DR

This paper investigates how nodal quasiparticles influence the superfluid density in underdoped cuprates, proposing a relation between critical temperature and superfluid density that aligns with recent experimental observations.

Contribution

It introduces a new relation between T_c and (0) that incorporates quasiparticle excitations and vortex fluctuations, explaining deviations from Uemura scaling in underdoped cuprates.

Findings

Nodal quasiparticles significantly affect superfluid density behavior.

The proposed T_c-(0) relation matches experimental data.

Deviations from Uemura scaling are explained by combined effects of quasiparticles and vortices.

Abstract

The combination of a large superconducting gap, low transition temperature, and quasi two-dimensionality in strongly underdoped high temperature superconductors severely constrains the behavior of the ab-plane superfluid density \rho with temperature T. In particular, we argue that the contribution of nodal quasiparticles to \rho(T) is essential to account both for the amplitude of, and the recently observed deviations from, the Uemura scaling. A relation between T_c and \rho(0) which combines the effects of quasiparticle excitations at low temperatures and of vortex fluctuations near the critical temperature is proposed and discussed in light of recent experiments.