Puphal Pascal, Wu Yu-Mi, Fürsich Katrin, Lee Hangoo, Pakdaman Mohammad, Bruin Jan A N, Nuss Jürgen, Suyolcu Y Eren, van Aken Peter A, Keimer Bernhard, Isobe Masahiko, Hepting Matthias
Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.
Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA.
Sci Adv. 2021 Dec 3;7(49):eabl8091. doi: 10.1126/sciadv.abl8091.
Topotactic transformations between related crystal structures are a powerful emerging route for the synthesis of novel quantum materials. Whereas most such “soft chemistry” experiments have been carried out on polycrystalline powders or thin films, the topotactic modification of single crystals, the gold standard for physical property measurements on quantum materials, has been studied only sparsely. Here, we report the topotactic reduction of LaCaNiO single crystals to LaCaNiO using CaH as the reducing agent. The transformation from the three-dimensional perovskite to the quasi–two-dimensional infinite-layer phase was thoroughly characterized by x-ray diffraction, electron microscopy, Raman spectroscopy, magnetometry, and electrical transport measurements. Our work demonstrates that the infinite-layer structure can be realized as a bulk phase in crystals with micrometer-sized single domains. The electronic properties of these specimens resemble those of epitaxial thin films rather than powders with similar compositions.
相关晶体结构之间的拓扑变换是合成新型量子材料的一种强大的新兴途径。尽管大多数此类“软化学”实验是在多晶粉末或薄膜上进行的，但作为量子材料物理性质测量的金标准——单晶的拓扑改性，却很少被研究。在此，我们报告了使用CaH作为还原剂将LaCaNiO单晶拓扑还原为LaCaNiO。通过X射线衍射、电子显微镜、拉曼光谱、磁强计和电输运测量对从三维钙钛矿到准二维无限层相的转变进行了全面表征。我们的工作表明，无限层结构可以在具有微米级单畴的晶体中实现为体相。这些样品的电子性质类似于外延薄膜，而不是具有相似成分的粉末。
