Configurable phonon polaritons in twisted α-MoO3
Configurable phonon polaritons in twisted α-MoO3
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DOI：
10.1038/s41563-020-0732-6
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发表时间：
2020-07-13
期刊：
影响因子：
41.2
通讯作者：
Dai, Siyuan
中科院分区：
文献类型：
--
作者：
Chen, Mingyuan;Lin, Xiao;Dai, Siyuan
扭曲的α相氧化钼双层膜中声子极化子的红外纳米成像揭示了扭曲的α相氧化钼双层膜中可调谐的波前几何结构和宽扭角范围内的拓扑跃迁，为纳米光子学的应用提供了一个可配置的平台。云纹工程作为一种调节扭曲的范德华材料的电子、磁学和光学性质的方法正在被广泛研究。莫尔工程的进展源于在小而特定的扭角下形成奇特的莫尔超晶格。在这里，我们报告了可配置的纳米级光物质波-声子极化子-通过在从0度到90度的广泛扭角范围内扭曲堆叠的阿尔法相三氧化钼(α-MoO_3)薄片。我们的实验和理论相结合的结果揭示了作为扭角的函数的各种极化激子波前几何结构和拓扑转变。与莫尔超晶格中电子能带结构变化的原因不同，极化激元扭转组态是由于层叠的α-MoO(3)层中高度各向异性的双曲极化激元的电磁相互作用所致。这些结果表明扭曲的α-MoO(3)有望成为具有可调谐功能的纳米光子器件的平台。
Infrared nanoimaging of phonon polaritons in twisted alpha-phase molybdenum trioxide bilayers reveals tunable wavefront geometries and topological transitions over a broad range of twist angles, offering a configurable platform for nanophotonic applications.Moire engineering is being intensively investigated as a method to tune the electronic, magnetic and optical properties of twisted van der Waals materials. Advances in moire engineering stem from the formation of peculiar moire superlattices at small, specific twist angles. Here we report configurable nanoscale light-matter waves-phonon polaritons-by twisting stacked alpha-phase molybdenum trioxide (alpha-MoO3) slabs over a broad range of twist angles from 0 degrees to 90 degrees. Our combined experimental and theoretical results reveal a variety of polariton wavefront geometries and topological transitions as a function of the twist angle. In contrast to the origin of the modified electronic band structure in moire superlattices, the polariton twisting configuration is attributed to the electromagnetic interaction of highly anisotropic hyperbolic polaritons in stacked alpha-MoO(3)slabs. These results indicate twisted alpha-MoO(3)to be a promising platform for nanophotonic devices with tunable functionalities.