Breakdown of the universal Josephson relation in spin ordered cuprate superconductors

TL;DR

This study investigates deviations from the universal Josephson relation in cuprate superconductors, linking these deviations to increased anisotropy and magnetic order development within the CuO2 planes.

Contribution

It reveals the breakdown of Josephson interlayer physics correlates with magnetic order, challenging the universality of the Josephson relation in these materials.

Findings

Violation of Josephson scaling observed

Enhanced anisotropy in superfluid density detected

Link established between magnetic order and Josephson relation breakdown

Abstract

We present \emph{c} axis infrared optical data on a number of Ba, Sr and Nd-doped cuprates of the La$_{2}$CuO$_{4}$ (La214) series in which we observe significant deviations from the universal Josephson relation linking the normal state transport (DC conductivity $\sigma_{DC}$ measured at $T_{c}$) with the superfluid density ($\rho_{s}$): $\rho_{s}\propto\sigma_{DC}(T_{c})$. We find the violation of Josephson scaling is associated with striking enhancement of the anisotropy in the superfluid density. The data allows us to link the breakdown of Josephson interlayer physics with the development of magnetic order in the CuO$_2$ planes.