Hu Kejun, Li Qing, Song Dongsheng, Jia Yingze, Liang Zhiyao, Wang Shuai, Du Haifeng, Wen Hai-Hu, Ge Binghui
Information Materials and Intelligent Sensing Laboratory of Anhui Province, Anhui Key Laboratory of Magnetic Functional Materials and Devices, Institutes of Physical Science and Information Technology, Anhui University, Hefei, China.
Center for Superconducting Physics and Materials, National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, China.
Nat Commun. 2024 Jun 14;15(1):5104. doi: 10.1038/s41467-024-49533-1.
The recent discovery of superconductivity in infinite-layer nickelate films has sparked significant interest and expanded the realm of superconductors, in which the infinite-layer structure and proper chemical doping are both of the essence. Nonetheless, the reasons for the absence of superconductivity in bulk infinite-layer nickelates remain puzzling. Herein, we investigate atomic defects and electronic structures in bulk infinite-layer NdSrNiO using scanning transmission electron microscopy. Our observations reveal the presence of three-dimensional (3D) block-like structural domains resulting from intersecting defect structures, disrupting the continuity within crystal grains, which could be a crucial factor in giving rise to the insulating character and inhibiting the emergence of superconductivity. Moreover, the infinite-layer structure, without complete topotactic reduction, retains interstitial oxygen atoms on the Nd atomic plane in bulk nickelates, possibly further aggravating the local distortions of NiO planes and hindering the superconductivity. These findings shed light on the existence of structural and atomic defects in bulk nickelates and provide valuable insights into the influence of proper topotactic reduction and structural orders on superconductivity.
最近在无限层镍酸盐薄膜中发现超导性引发了极大的兴趣，并扩展了超导体的领域，其中无限层结构和适当的化学掺杂都至关重要。尽管如此，块状无限层镍酸盐中不存在超导性的原因仍然令人费解。在此，我们使用扫描透射电子显微镜研究块状无限层NdSrNiO中的原子缺陷和电子结构。我们的观察结果揭示了由相交缺陷结构导致的三维（3D）块状结构域的存在，破坏了晶粒内的连续性，这可能是导致绝缘特性并抑制超导性出现的关键因素。此外，在没有完全拓扑还原的情况下，无限层结构在块状镍酸盐的Nd原子平面上保留了间隙氧原子，这可能进一步加剧NiO平面的局部畸变并阻碍超导性。这些发现揭示了块状镍酸盐中结构和原子缺陷的存在，并为适当的拓扑还原和结构有序对超导性的影响提供了有价值的见解。
