Resolving the polar interface of infinite-layer nickelate thin films
Resolving the polar interface of infinite-layer nickelate thin films
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DOI：
10.1038/s41563-023-01510-7
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发表时间：
2023-03-27
期刊：
影响因子：
41.2
通讯作者：
Kourkoutis, Lena F. F.
中科院分区：
文献类型：
--
作者：
Goodge, Berit H. H.;Geisler, Benjamin;Kourkoutis, Lena F. F.
镍基超导体提供了一个期待已久的实验平台来探索可能的类铜超导性。然而，尽管具有相似的晶体结构和 d 电子填充，镍盐中的超导性迄今为止仅在薄膜几何形状中稳定，这引发了有关基板和薄膜之间极性界面的问题。在这里，我们对 Nd1-xSrxNiO2 和 SrTiO3 之间的原型界面进行了详细的实验和理论研究。扫描透射电子显微镜中的原子分辨率电子能量损失光谱揭示了单个中间 Nd(Ti,Ni)O-3 层的形成。使用哈伯德 U 项进行的密度泛函理论计算显示了观察到的结构如何减轻极性不连续性。我们探索了氧占据、空穴掺杂和阳离子结构的影响，以理清每种因素对降低界面电荷密度的贡献。解决这一重要的界面结构对于未来在其他基底和垂直异质结构上合成镍盐薄膜具有指导意义。迄今为止，镍酸盐超导性仅限于薄膜，这引发了有关极性基底-薄膜界面作用的问题。在这里，作者利用先进的表征技术来揭示界面原子结构及其与超导性的相关性。
Nickel-based superconductors provide a long-awaited experimental platform to explore possible cuprate-like superconductivity. Despite similar crystal structure and d electron filling, however, superconductivity in nickelates has thus far only been stabilized in thin-film geometry, raising questions about the polar interface between substrate and thin film. Here we conduct a detailed experimental and theoretical study of the prototypical interface between Nd1-xSrxNiO2 and SrTiO3. Atomic-resolution electron energy loss spectroscopy in the scanning transmission electron microscope reveals the formation of a single intermediate Nd(Ti,Ni)O-3 layer. Density functional theory calculations with a Hubbard U term show how the observed structure alleviates the polar discontinuity. We explore the effects of oxygen occupancy, hole doping and cation structure to disentangle the contributions of each for reducing interface charge density. Resolving the non-trivial interface structure will be instructive for future synthesis of nickelate films on other substrates and in vertical heterostructures.Nickelate superconductivity has so far been limited to thin films, raising questions about the role of the polar substrate-film interface. Here the authors utilize advanced characterization techniques to reveal the interfacial atomic structure and its relevance for superconductivity.