发表机构
Molecular Foundry, Lawrence Berkeley National Laboratory; School for Engineering of Matter, Transport and Energy, Arizona State University; Department of Physics, University of Texas at Austin; National Institute for Materials Science; Center for Nanophase Materials Sciences, Oak Ridge National Laboratory; Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin; McKetta Department of Chemical Engineering, The University of Texas at Austin; Kavli Energy NanoScience Institute, University of California Berkeley; Jawaharlal Nehru Centre for Advanced Scientific Research（劳伦斯伯克利国家实验室分子发现中心; 亚利桑那州立大学物质、运输与能源工程学院; 德克萨斯大学奥斯汀分校物理系; 日本国立材料研究所; 橡树岭国家实验室纳米材料科学中心; 德克萨斯大学奥斯汀分校奥登计算工程与科学学院; 德克萨斯大学奥斯汀分校麦凯塔化学工程系; 加州大学伯克利分校卡弗里能源纳米科学研究所; 贾瓦哈拉尔·尼赫鲁高级科学研究中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过低温单色电子能量损失谱、第一性原理GW-BSE计算和光学光谱，实空间揭示了WSe2/WS2莫尔超晶格中结构重构程度调控激子局域化与退局域化的机制，并指出新共振不足以判定局域化，为莫尔激子工程提供新原则。
AI 中文摘要
光学吸收和发射中的光谱指纹通常被用作扭曲莫尔双层中激子局域化的标志。然而，激子被限制在特定堆叠位点的机制及其相关的光学特征在实验上仍未得到解决。在此，我们直接在实空间中可视化调控结构重构程度的变化如何导致WSe2/WS2莫尔超晶格中莫尔激子的局域化与退局域化。利用低温单色电子能量损失谱，结合第一性原理GW-贝特-萨尔皮特方程计算和光学光谱学，我们揭示了驱动扭角相关结构转变、莫尔激子实空间局域化及其光学特征之间关联的物理机制。令人惊讶的是，与主流理解相反，我们表明光学光谱中新的莫尔激子共振的出现本身不足以确立激子局域化。相反，结构重构的程度和外部应变驱动激子局域化，从而为工程化莫尔激子和应变敏感的量子光电器件提供了新的设计原则。
英文摘要
Spectral fingerprints in optical absorption and emission have typically been used as a signature of exciton localization in twisted moiré bilayers. However, the mechanism by which excitons become confined to specific stacking sites and their associated optical signature is experimentally unresolved. Here, we directly visualize in real space how tuning the change in extent of structural reconstruction leads to localization and delocalization of moiré excitons in the WSe2/WS2 moiré superlattice. Using cryogenic monochromated electron energy loss spectroscopy, together with first-principles GW-Bethe Salpeter equation calculations and optical spectroscopy, we uncover the physical mechanism that drives the correlation between twist-angle-dependent structural transformations, the real-space localization of moiré excitons, and their optical signatures. Surprisingly, and in contrast to the prevailing understanding, we show that the emergence of new moiré exciton resonances in the optical spectra alone is insufficient to establish exciton localization. Instead, the extent of structural reconstruction and external strain drives exciton localization, leading to new design principles for engineering moiré excitons and strain-aware quantum optoelectronic devices.
CommentsFinal three authors are corresponding authors, First three authors gave equal contribution
