- Parzyck, CT;
- Gupta, NK;
- Wu, Y;
- Anil, V;
- Bhatt, L;
- Bouliane, M;
- Gong, R;
- Gregory, BZ;
- Luo, A;
- Sutarto, R;
- He, F;
- Chuang, Y-D;
- Zhou, T;
- Herranz, G;
- Kourkoutis, LF;
- Singer, A;
- Schlom, DG;
- Hawthorn, DG;
- Shen, KM
A hallmark of many unconventional superconductors is the presence of many-body interactions that give rise to broken-symmetry states intertwined with superconductivity. Recent resonant soft X-ray scattering experiments report commensurate 3a0 charge density wave order in infinite-layer nickelates, which has important implications regarding the universal interplay between charge order and superconductivity in both cuprates and nickelates. Here we present X-ray scattering and spectroscopy measurements on a series of NdNiO2+x samples, which reveal that the signatures of charge density wave order are absent in fully reduced, single-phase NdNiO2. The 3a0 superlattice peak instead originates from a partially reduced impurity phase where excess apical oxygens form ordered rows with three-unit-cell periodicity. The absence of any observable charge density wave order in NdNiO2 highlights a crucial difference between the phase diagrams of cuprate and nickelate superconductors.