High-Temperature Charge-Stripe Correlations in La${}_{1.675}$Eu${}_{0.2}$Sr${}_{0.125}$CuO${}_4$

Abstract

We use resonant inelastic x-ray scattering to investigate charge-stripe correlations in La${}_{1.675}$Eu${}_{0.2}$Sr${}_{0.125}$CuO${}_4$. By differentiating elastic from inelastic scattering, it is demonstrated that charge-stripe correlations precede both the structural low-temperature tetragonal phase and the transport-defined pseudogap onset. The scattering peak amplitude from charge stripes decays approximately as $T^{-2}$ towards our detection limit. The in-plane integrated intensity, however, remains roughly temperature independent. Therefore, although the incommensurability shows a remarkably large increase at high temperature, our results are interpreted via a single scattering constituent. In fact, direct comparison to other stripe-ordered compounds (La${}_{1.875}$Ba${}_{0.125}$CuO${}_4$, La${}_{1.475}$Nd${}_{0.4}$Sr${}_{0.125}$CuO${}_4$ and La${}_{1.875}$Sr${}_{0.125}$CuO${}_4$) suggests a roughly constant integrated scattering intensity across all these compounds. Our results therefore provide a unifying picture for the charge-stripe ordering in La-based cuprates. As charge correlations in La${}_{1.675}$Eu${}_{0.2}$Sr${}_{0.125}$CuO${}_4$ extend beyond the low-temperature tetragonal and pseudogap phase, their emergence heralds a spontaneous symmetry breaking in this compound.