论文标题
扭曲的2D Homo/杂型 - bilayers中晶格动力学的签名
Signature of lattice dynamics in twisted 2D homo/hetero-bilayers
论文作者
论文摘要
扭曲的2D双层材料是通过人工堆叠的两个单层晶体网络，这些单层晶体网络的2D材料具有所需的扭曲角$θ$。由于顶层和底层晶体结构的周期性，该材料形成了Moiré超晶格。光学特性是通过晶格重建和声子重归于的，这使光谱成为研究新型物理现象的理想特征工具。在这里，我们报告了对整个扭曲的双层（TB）WSE $ _2 $ MOIRRE SUPERATTICE（\ TEXTIT，即0°$ \leqθ\ leq $ 60°）的拉曼调查。我们观察到两个拉曼峰的强度比，$ b_ {2g} $和$ e_ {2g}/a_ {1g} $与Moiré时期的演变相关。拉曼强度比扭曲角的函数遵循指数曲线，将莫伊尔期与0°和60°的两个局部最大值匹配，最小值在30°。 Using a series of temperature-dependent Raman and photoluminescence (PL) measurements as well as \textit{ab initio} calculations, the intensity ratio $I_{B_{2g}}/I_{E_{2g}/{A_{1g}}}$ is explained as a signature of lattice dynamics in tB WSe$_2$ moiré超晶格。通过进一步探索扭曲异质双层的不同材料组合，对于各种基于MO的TMDC，将扩展结果。
Twisted 2D bilayer materials are created by artificial stacking of two monolayer crystal networks of 2D materials with a desired twisting angle $θ$. The material forms a moiré superlattice due to the periodicity of both top and bottom layer crystal structure. The optical properties are modified by lattice reconstruction and phonon renormalization, which makes optical spectroscopy an ideal characterization tool to study novel physics phenomena. Here, we report a Raman investigation on a full period of the twisted bilayer (tB) WSe$_2$ moiré superlattice (\textit i.e. 0° $\leq θ\leq$ 60°). We observe that the intensity ratio of two Raman peaks, $B_{2g}$ and $E_{2g}/A_{1g}$ correlates with the evolution of moiré period. The Raman intensity ratio as a function of twisting angle follows an exponential profile matching the moiré period with two local maxima at 0° and 60° and a minimum at 30°. Using a series of temperature-dependent Raman and photoluminescence (PL) measurements as well as \textit{ab initio} calculations, the intensity ratio $I_{B_{2g}}/I_{E_{2g}/{A_{1g}}}$ is explained as a signature of lattice dynamics in tB WSe$_2$ moiré superlattices. By further exploring different material combinations of twisted hetero-bilayers, the results are extended for all kinds of Mo- and W-based TMDCs.
