论文标题
薄膜超导无限层镍的合成方面
Aspects of the Synthesis of Thin Film Superconducting Infinite-Layer Nickelates
论文作者
论文摘要
最近对ND $ _ {0.8} $ sr $ _ {0.2} $ nio $ _ {2} $调用的超导性观察，以进一步调查和优化这种亚稳态的无限层镍镍结构。在这里，我们介绍了我们对父母钙钛矿化合物生长的重要方面的理解，该化合物通过脉冲激光沉积在srtio $ _ {3} $（001）底物上以及随后的拓扑减少。我们发现，要实现单晶，单相超导nd $ _ {0.8} $ sr $ _ {0.2} $ nio $ _ {2} $，前提是perovskite perovskite nd $ _ {0.8} $ _ {0.8} $ sr $ _ {0.2 $ _ {0.2 $ nio $ _ {3.3 io tinl tinl tinl and tinl and tinl and tinl and {3.3}杂质阶段；特别是，经常观察到Ruddlesden-Popper型次级。我们进一步研究了软化学拓扑还原条件的演变，以实现向无限层结构的完全转化，而没有膜分解或其他阶段的形成。我们发现，用随后的srtio $ _ {3} $ layer限制镍胶片，为镍膜的顶部区域提供了外延模板，就像基板一样。因此，对于当前优化的增长条件，我们可以稳定超导单相nd $ _ {0.8} $ sr $ _ {0.2} $ nio $ _ {2} $（001）外生薄膜最多约为10 nm。
The recent observation of superconductivity in Nd$_{0.8}$Sr$_{0.2}$NiO$_{2}$ calls for further investigation and optimization of the synthesis of this metastable infinite-layer nickelate structure. Here, we present our current understanding of important aspects of the growth of the parent perovskite compound via pulsed laser deposition on SrTiO$_{3}$ (001) substrates, and the subsequent topotactic reduction. We find that to achieve single-crystalline, single-phase superconducting Nd$_{0.8}$Sr$_{0.2}$NiO$_{2}$, it is essential that the precursor perovskite Nd$_{0.8}$Sr$_{0.2}$NiO$_{3}$ thin film is stabilized with high crystallinity and no impurity phases; in particular, a Ruddlesden-Popper-type secondary phase is often observed. We have further investigated the evolution of the soft-chemistry topotactic reduction conditions to realize full transformation to the infinite-layer structure with no film decomposition or formation of other phases. We find that capping the nickelate film with a subsequent SrTiO$_{3}$ layer provides an epitaxial template to the top region of the nickelate film, much like the substrate. Thus, for currently optimized growth conditions, we can stabilize superconducting single-phase Nd$_{0.8}$Sr$_{0.2}$NiO$_{2}$ (001) epitaxial thin films up to ~ 10 nm.
