# Static Charge Density Wave Order in the Superconducting State of La2-xBaxCuO4

## TL;DR

This study demonstrates that static charge density wave order coexists with superconductivity in La$_{2-x}$Ba$_x$CuO$_4$, persisting at low temperatures and up to high fractions of the transition temperature, challenging the notion of purely competing orders.

## Contribution

First direct observation of static CDW order coexisting with superconductivity in La$_{2-x}$Ba$_x$CuO$_4$ using resonant x-ray photon correlation spectroscopy.

## Key findings

- Static CDW order exists in the superconducting state.
- CDW correlations persist up to at least 85% of the transition temperature.
- Implications for coexistence of competing order parameters in cuprates.

## Abstract

Charge density wave (CDW) correlations feature prominently in the phase diagram of the cuprates, motivating competing theories of whether fluctuating CDW correlations aid superconductivity or whether static CDW order coexists with superconductivity in inhomogeneous or spatially modulated states. Here we report Cu $L$-edge resonant x-ray photon correlation spectroscopy (XPCS) measurements of CDW correlations in superconducting La$_{2-x}$Ba$_x$CuO$_4$ $x=0.11$. Static CDW order is shown to exist in the superconducting state at low temperatures and to persist up to at least 85\% of the CDW transition temperature. We discuss the implications of our observations for how \emph{nominally} competing order parameters can coexist in the cuprates.