Screening in anisotropic superfluids and the superfluid density in underdoped cuprates

TL;DR

This paper investigates collective excitations and superfluid density behavior in anisotropic bosonic systems with Coulomb interactions, modeling underdoped cuprates and identifying four regimes influenced by anisotropy and interaction strength.

Contribution

It provides a detailed analysis of how anisotropy and Coulomb interaction strength affect superfluid density regimes in models of underdoped cuprates.

Findings

Four distinct temperature dependence regimes for superfluid density.

Coulomb interaction in underdoped cuprates is effectively short-ranged.

Superfluid density behavior depends on anisotropy and interaction strength.

Abstract

We examine the nature of the collective excitations in a strongly anisotropic system of bosons interacting via Coulomb interaction. Such a system has often been used in the past to model the effects of quantum and classical phase fluctuations on the superfluid density of underdoped cuprates. Depending on the anisotropy and the effective strength of the interaction we find four different regimes for the temperature dependence of the superfluid density. Coulomb interaction in underdoped cuprates is argued to be effectively short-ranged, and of order of unity in appropriately defined units.