Charge ordering in electron-doped infinite-layer cuprate Sr$_{1-x}$La$_x$CuO$_2$

Charge ordering has emerged as a likely candidate for a universal ordering parameter in both hole- and electron-doped cuprates. In the electron-doped cuprates, however, charge order has only been detected in the R$_{2-x}$Ce$_x$CuO$_4$ (R=La,Nd) family. With its simple structure lacking both structural distortions and magnetic ions, the infinite-layer cuprate Sr$_{1-x}$La$_x$CuO$_2$ represents an important model system for studying charge ordering in electron-doped cuprates. Here, we use resonant elastic x-ray scattering to study charge ordering in Sr$_{1-x}$La$_x$CuO$_2$. Using a quantitative model to account for the fluorescent background, we detect signatures of charge order in several samples with doping near x=0.07. We find the ordering wavevector of the charge order to be Q=(0.13$\pm$0.02, 0, L), significantly smaller than has been observed in other cuprates. We discuss the relationship between the charge order and the Fermi surface in this material.