Comparison of charge modulations in La$_{1.875}$Ba$_{0.125}$CuO$_4$ and YBa$_2$Cu$_3$O$_{6.6}$

TL;DR

This study compares charge modulations in two cuprate superconductors, revealing similar order parameters but differing correlation lengths, advancing understanding of charge order phenomena in high-temperature superconductors.

Contribution

It provides a direct comparison of lattice charge modulations in La$_{1.875}$Ba$_{0.125}$CuO$_4$ and YBa$_2$Cu$_3$O$_{6.6}$ using soft x-ray scattering, highlighting similarities in order parameters.

Findings

Correlation length in La$_{1.875}$Ba$_{0.125}$CuO$_4$ is approximately 259 Å.

Correlation length in YBa$_2$Cu$_3$O$_{6.6}$ is approximately 55 Å.

Order parameters of lattice modulations are of similar magnitude in both compounds.

Abstract

A charge modulation has recently been reported in (Y,Nd)Ba$_2$Cu$_3$O$_{6+x}$ [Ghiringhelli {\em et al.} Science 337, 821 (2013)]. Here we report Cu $L_3$ edge soft x-ray scattering studies comparing the lattice modulation associated with the charge modulation in YBa$_2$Cu$_3$O$_{6.6}$ with that associated with the well known charge and spin stripe order in La$_{1.875}$Ba$_{0.125}$CuO$_4$. We find that the correlation length in the CuO$_2$ plane is isotropic in both cases, and is $259 \pm 9$ \AA for La$_{1.875}$Ba$_{0.125}$CuO$_4$ and $55 \pm 15$ \AA for YBa$_2$Cu$_3$O$_{6.6}$. Assuming weak inter-planar correlations of the charge ordering in both compounds, we conclude that the order parameters of the lattice modulations in La$_{1.875}$Ba$_{0.125}$CuO$_4$ and YBa$_2$Cu$_3$O$_{6.6}$ are of the same order of magnitude.