论文标题
金属稀释的二聚体二聚化
Metallic Diluted Dimerization in VO2 Tweeds
论文作者
论文摘要
二氧化钒（VO2）（一种原型电子相关的氧化物）中电子相分离纹理的观察，最近在有关其金属绝缘体过渡及其应用的长期存在的辩论中增加了新的观点。然而，伴随这种复杂模式的阶段缺乏原子分辨的信息仍然阻碍了对过渡及其在实际设备中的实施的全面理解。在这项工作中，原子分辨率成像和光谱学揭示了〜5 nm长度尺度上的铁弹性旋转结构的存在，远低于当前使用的光谱成像技术的分辨率极限。此外，密度功能理论的计算表明，这种精细的花呢是由金属结构形成的，该金属结构是由部分二聚V链形成的，平均是四方（金红石），但在局部是单斜的。这些观察结果表明，低对称形式的VO2之间的金属/绝缘体共存是由晶格的自由度驱动的，并为解释现有数据提供了多尺度的观点，从而可以一方面发生相位的相结合和结构上的混合，直到下降到原子尺度。
The observation of electronic phase separation textures in vanadium dioxide (VO2), a prototypical electron-correlated oxide, has recently added new perspectives on the long standing debate about its metal-insulator transition and its applications. Yet, the lack of atomically-resolved information on phases accompanying such complex patterns still hinders a comprehensive understanding of the transition and its implementation in practical devices. In this work, atomic resolution imaging and spectroscopy unveils the existence of ferroelastic tweed structures on ~5 nm length scales, well below the resolution limit of currently employed spectroscopic imaging techniques. Moreover, density functional theory calculations show that such fine tweeds are formed by a metallic structure, formed by partially dimerized V-chains, that appears tetragonal (rutile) on average, but is locally monoclinic. These observations suggest that the metal/insulator coexistence among low-symmetry forms of VO2 is driven by lattice degrees of freedom, and provide a multiscale perspective for the interpretation of existing data, whereby phase coexistence and structural intermixing can occur all the way down to the atomic scale.
