Percolative nature of the dc paraconductivity in the cuprate superconductors

TL;DR

This paper investigates the dc paraconductivity in underdoped cuprate superconductors, revealing an exponential temperature dependence explained by a percolation model that highlights the role of gap disorder in superconductivity emergence.

Contribution

It demonstrates that the paraconductivity's unusual behavior can be quantitatively explained by a superconducting percolation model considering gap disorder.

Findings

Paraconductivity shows exponential temperature dependence.

A simple percolation model explains the data.

Gap disorder influences superconductivity onset.

Abstract

We present an investigation of the planar direct-current (dc) paraconductivity of the model cuprate material HgBa$_2$CuO$_{4+\delta}$ in the underdoped part of the phase diagram. The simple quadratic temperature-dependence of the Fermi-liquid normal-state resistivity enables us to extract the paraconductivity above the macroscopic $T_c$ with great accuracy. The paraconductivity exhibits unusual exponential temperature dependence, with a characteristic temperature scale that is distinct from $T_c$. In the entire temperature range where it is discernable, the paraconductivity is quantitatively explained by a simple superconducting percolation model, which implies that underlying gap disorder dominates the emergence of superconductivity.