A charge modulation has recently been reported in (Y,Nd)Ba${}_2$Cu${}_3$O${}_{6+x}$ [G. Ghiringhelli et al., Science 337, 821 (2012)]. 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 $259\pm 9$ Å for La${}_{1.875}$Ba${}_{0.125}$CuO${}_4$ and $55\pm 15$ Å for YBa${}_2$Cu${}_3$O${}_{6.6}$. Assuming weak interplanar 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.

• Received 23 May 2013

DOI:https://doi.org/10.1103/PhysRevB.88.024505