  Although all superconducting cuprates display charge-ordering tendencies,
their low-temperature properties are distinct, impeding efforts to understand
the phenomena within a single conceptual framework. While some systems exhibit
stripes of charge and spin, with a locked periodicity, others host charge
density waves (CDWs) without any obviously related spin order. Here we use
resonant inelastic x-ray scattering (RIXS) to follow the evolution of charge
correlations in the canonical stripe ordered cuprate
La$_{1.875}$Ba$_{0.125}$CuO$_{4}$ (LBCO~$1/8$) across its ordering transition.
We find that high-temperature charge correlations are unlocked from the
wavevector of the spin correlations, signaling analogies to CDW phases in
various other cuprates. This indicates that stripe order at low temperatures is
stabilized by the coupling of otherwise independent charge and spin density
waves, with important implications for the relation between charge and spin
correlations in the cuprates.
