%0 Journal Article
%A Oppliger, Jens
%A Küspert, Julia
%A Dippel, Ann-Christin
%A v. Zimmermann, Martin
%A Gutowski, Olof
%A Ren, Xiaolin
%A Zhou, Xingjiang
%A Zhu, Zhihai
%A Frison, Ruggero
%A Wang, Qisi
%A Martinelli, Leonardo
%A Biało, Izabela
%A Chang, Johan
%T Discovery of giant unit-cell super-structure in the infinite-layer nickelate PrNiO<sub>2+x</sub>
%J Communications materials
%V 6
%N 1
%@ 2662-4443
%C London
%I Springer Nature
%M PUBDB-2025-00169
%P 3
%D 2025
%X The discovery of unconventional superconductivity often triggers significant interest in associated electronic and structural symmetry breaking phenomena. For the infinite-layer nickelates, structural allotropes are investigated intensively. Here, using high-energy grazing-incidence x-ray diffraction, we demonstrate how in-situ temperature annealing of the infinite-layer nickelate PrNiO<sub>2+x</sub> (x ≈ 0) induces a giant superlattice structure. The annealing effect has a maximum well above room temperature. By covering a large scattering volume, we show a rare period-six in-plane (bi-axial) symmetry and a period-four symmetry in the out-of-plane direction. This giant unit-cell superstructure—likely stemming from ordering of diffusive oxygen—persists over a large temperature range and can be quenched. As such, the stability and controlled annealing process leading to the formation of this superlattice structure provides a pathway for novel nickelate chemistry. 
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:39780911
%U <Go to ISI:>//WOS:001390550100001
%R 10.1038/s43246-024-00729-4
%U https://bib-pubdb1.desy.de/record/622083