Valley-optical properties in layered 2D transition metal dichalcogenides

• Main Author: Huang, Zumeng
• Other Authors: Gao Weibo
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Science::Physics::Atomic physics::Solid state physics
• Online Access: https://hdl.handle.net/10356/151689
• Institution: Nanyang Technological University

Two-dimensional Transition Metal Dichalcogenides (TMDs) are a group of materials that draws intensive research interests because of their unique valley contrasting physics, in the application of next generation spintronics and valleytronics. Recently, the stacking of 2D TMDs to form heterostructures of layered TMDs have shown enhanced spin-valley phenomenon including longer exciton lifetime and valley lifetime. They also feature strong electron-electron correlation in the vicinity of Mott transition density for heterostructures with a moiré potential. All these properties provide opportunities for deeper understanding of TMDs valley physics. Here in this thesis, three aspects of the valley-optical physics in layered TMDs heterostructures is presented. Firstly, the Zeeman splitting for right-handed and left-handed emission for bilayer MoTe2 in strong magnetic field is shown. In such inversion symmetry persevering system, because of spin-valley-layer locking effect the valley Zeeman splitting would be significant different from the monolayer counterpart. This enables the possibility for magnetic field control bilayer-based valley electro-optical devices. Secondly, the interlayer exciton valley Hall effect (VHE) is investigated and presented. Comparing with the monolayer version of VHE which remains to be a low temperature phenomenon, interlayer exciton VHE can be observed for even room temperature, which paves the way for practical TMDs-based topological information devices. Thirdly, the heterostructure formed by putting a TMDs monolayer on top of another multilayer is stated. As exploited with the band structure modification under different layer numbers, the PL emission under such configuration of TMDs heterostructure reflects band edge energy in semiconducting materials, which would otherwise experimentally detected by much more sophisticated methods like ARPES. Lastly, some future perspectives related with the strong correlation and moiré excitons is presented.