Real-space investigation of the charge density wave in VTe2 monolayer with broken rotational and mirror symmetries
Real-space investigation of the charge density wave in VTe2 monolayer with broken rotational and mirror symmetries
复制标题
旋转对称和镜像对称破缺的 VTe2 单层中电荷密度波的实空间研究
DOI：
10.1103/physrevb.101.035407
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发表时间：
2020-01-08
影响因子：
3.7
通讯作者：
Guo, Jiandong
中科院分区：
文献类型：
--
作者：
Miao, Guangyao;Xue, Siwei;Guo, Jiandong
近年来，钒二盐化合物中的电荷密度波(CDW)引起了越来越多的研究兴趣，但对VTe2单层中CDW态对称性破缺的实空间研究还很少。我们用低能电子衍射(LEED)和扫描隧道显微镜(STM)研究了VTe2单层的CDW。虽然LEED实验揭示了192K附近的(4×4)CDW跃迁，但我们的低温STM实验解决了真实空间中的(4×4)晶格扭曲和电荷密度调制，并进一步揭示了一维结构调制，它打破了CDW态的三重旋转对称性和镜面对称性。根据低温下的CDW态，用扫描隧道谱在4.9K下探测到了12 meV的CDW能隙。对称性破缺表明，除了传统的费米面嵌套或依赖于Q的电声子耦合外，一些其他机制也可能有助于打破VTe2单分子膜CDW态的三重旋转对称性。
Recently the charge density wave (CDW) in vanadium dichalcogenides have attracted increasing research interest, but a real-space investigation on the symmetry breaking of the CDW state in VTe2 monolayer is still lacking. We have investigated the CDW of VTe2 monolayer by low energy electron diffraction (LEED) and scanning tunneling microscope (STM). While the LEED experiments revealed a (4 x 4) CDW transition near 192 K, our low-temperature STM experiments resolved the (4 x 4) lattice distortions and charge-density modulation in real space, and further unveiled a one-dimensional structural modulation that breaks the threefold rotational and mirror symmetries in the CDW state. In accordance with the CDW state at low temperature, a CDW gap of 12 meV was detected by scanning tunneling spectroscopy at 4.9 K. The observed symmetry breaking implies that besides the conventional Fermi surface nesting or the q-dependent electron-phonon coupling, some other mechanism may also contribute to breaking the threefold rotational symmetry in the CDW state of VTe2 monolayer.