Gonano Bruno, Fjellvåg Øystein Slagtern, Steciuk Gwladys, Saha Dipankar, Pelloquin Denis, Fjellvåg Helmer
Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, 0315, Oslo, Norway.
Department for Neutron Materials Characterization, Institute for Energy Technology, PO Box 40, 2027, Kjeller, Norway.
Angew Chem Int Ed Engl. 2020 Dec 7;59(50):22382-22387. doi: 10.1002/anie.202006135. Epub 2020 Oct 13.
In this work we benefited from recent advances in tools for crystal-structure analysis that enabled us to describe an exotic nanoscale phenomenon in structural chemistry. The Mn Ni As sample of the Mn Ni As solid solution, exhibits an incommensurate compositional modulation intimately coupled with positional modulations. The average structure is of the simple NiAs type, but in contrast to a normal solid solution, we observe that manganese and nickel segregate periodically at the nano-level into ordered MnAs and NiAs layers with thickness of 2-4 face-shared octahedra. The detailed description was obtained by combination of 3D electron diffraction, scanning transmission electron microscopy, and neutron diffraction. The distribution of the manganese and nickel layers is perfectly described by a modulation vector q=0.360(3) c*. Displacive modulations are observed for all elements as a consequence of the occupational modulation, and as a means to achieve acceptable Ni-As and Mn-As distances. This modulated evolution of magnetic MnAs and non-magnetic NiAs-layers with periodicity at approximately 10 Å level, may provide an avenue for spintronics.
在这项工作中，我们受益于晶体结构分析工具的最新进展，这些进展使我们能够描述结构化学中一种奇特的纳米级现象。MnNiAs固溶体的MnNiAs样品表现出与位置调制紧密耦合的非公度成分调制。平均结构为简单的NiAs型，但与普通固溶体不同的是，我们观察到锰和镍在纳米尺度上周期性地分离成厚度为2 - 4个共面八面体的有序MnAs和NiAs层。通过结合三维电子衍射、扫描透射电子显微镜和中子衍射获得了详细描述。锰和镍层的分布由调制矢量q = 0.360(3) c*完美描述。由于占位调制，所有元素都观察到了位移调制，这是实现可接受的Ni - As和Mn - As距离的一种方式。这种磁性MnAs和非磁性NiAs层在约10 Å水平上具有周期性的调制演化，可能为自旋电子学提供一条途径。
