Determination of Crystal Axes in Semimetallic T′‐MoTe2 by Polarized Raman Spectroscopy
Determination of Crystal Axes in Semimetallic T′‐MoTe2 by Polarized Raman Spectroscopy
复制标题
DOI：
10.1002/adfm.201604799
复制
发表时间：
2017-03
影响因子：
19
通讯作者：
Junyong Wang;Xin Luo;Shisheng Li;I. Verzhbitskiy;Weijie Zhao;Shunfeng Wang;S. Y. Quek;G. Eda
中科院分区：
文献类型：
--
作者：
Junyong Wang;Xin Luo;Shisheng Li;I. Verzhbitskiy;Weijie Zhao;Shunfeng Wang;S. Y. Quek;G. Eda
扭曲的八面体T‘相MoTe2由于其预测的拓扑态和新颖的电荷输运性质最近引起了人们的极大兴趣。在这里，我们报道了一种用偏振拉曼光谱无损地确定几层T‘-MoTe2薄片晶体取向的方法。实验观测到的拉曼模被指定为密度泛函理论计算所预测的振动本征模。偏振拉曼测量揭示了四种不同类型的与角度相关的强度变化。从群论可以推断，当入射光的偏振矢量平行或垂直于金属-金属之字链方向时，BG模的强度在x‘(Yz)x位形上达到最大值。BG模的强度变化不能用来明确地确定晶体取向。电子衍射分析表明，当入射光的偏振矢量平行于x‘(Yy)x组态中的金属-金属链方向时，在162 cm−1附近的Ag模的强度达到最大。此外，还提出了一种在非偏振拉曼光谱中识别晶体取向的简单方法。
Distorted octahedral T′ phase of MoTe2 has recently attracted significant interest due to its predicted topological states and novel charge transport properties. Here, we report a nondestructive method for determining the crystal orientation of few‐layer T′‐MoTe2 flakes by polarized Raman spectroscopy. The experimentally observed Raman modes are assigned to eigenmodes of vibrations predicted by density functional theory calculations. Polarized Raman measurements reveal four distinct types of angle‐dependent intensity variations. From group theory, it can be deduced that the intensity of the Bg mode reaches a maximum in the x¯(yz)x configuration when the polarization vector of the incident light is either parallel or orthogonal to the metal–metal zigzag chain direction. The intensity variation of the Bg mode cannot be used to unambiguously determine the crystal orientation. Using electron diffraction analysis, it is demonstrated that the intensity of the Ag mode at around 162 cm−1 reaches a maximum when the polarization vector of the incident light is parallel to the metal–metal chain direction in the x¯(yy)x configuration. Furthermore, a simple method is proposed for identifying crystal orientation in nonpolarized Raman spectroscopy.