Oppliger Jens, Küspert Julia, Dippel Ann-Christin, V Zimmermann Martin, Gutowski Olof, Ren Xiaolin, Zhou Xingjiang, Zhu Zhihai, Frison Ruggero, Wang Qisi, Martinelli Leonardo, Biało Izabela, Chang Johan
Physik-Institut, Universität Zürich, Zürich, Switzerland.
Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany.
Commun Mater. 2025;6(1):3. doi: 10.1038/s43246-024-00729-4. Epub 2025 Jan 7.
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 ( ≈ 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.
非常规超导性的发现常常引发人们对相关电子和结构对称性破缺现象的浓厚兴趣。对于无限层镍酸盐，人们对其结构变体进行了深入研究。在此，我们利用高能掠入射X射线衍射，展示了无限层镍酸盐PrNiO（≈0）的原位温度退火如何诱导出巨大的超晶格结构。退火效应在远高于室温时达到最大值。通过覆盖较大的散射体积，我们展示了罕见的面内（双轴）六重对称性和垂直于平面方向的四重对称性。这种巨大的晶胞超结构——可能源于扩散氧的有序排列——在较大的温度范围内持续存在且可以被淬火。因此，导致这种超晶格结构形成的稳定性和可控退火过程为新型镍酸盐化学提供了一条途径。
