期刊
NATURE MATERIALS
卷 14, 期 3, 页码 290-294出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/nmat4156
关键词
-
类别
资金
- US Department of Energy (DOE) award [DE-FG02-08ER46521, DE-SC0006423]
- NSF [DMR 0845358, DMR-1231319]
- Ministry of Science and Technology of the Republic of China [103-2112-M-007-001-MY3]
- STC Center for Integrated Quantum Materials (CIQM)
- U.S. Department of Energy (DOE) [DE-SC0006423] Funding Source: U.S. Department of Energy (DOE)
Breaking space-time symmetries in two-dimensional crystals can markedly influence their macroscopic electronic properties. Monolayer transition metal dichalcogenides (TMDs) are prime examples where the intrinsically broken crystal inversion symmetry permits the generation of valley-selective electron populations(1-4), even though the two valleys are energetically degenerate, locked by time-reversal symmetry. Lifting the valley degeneracy in these materials is of great interest because itwould allowfor valley-specific band engineering and offer additional control in valleytronic applications. Although applying a magnetic field should, in principle, accomplish this task, experiments so far have not shown valley-selective energy level shifts in fields accessible in the laboratory. Here, we show the first direct evidence of lifted valley degeneracy in the monolayer TMD WS2. By applying intense circularly polarized light, which breaks time-reversal symmetry, we demonstrate that the exciton level in each valley can be selectively tuned by as much as 18meV through the optical Stark effect. These results offer a newway to control the valley degree of freedom, and may provide a means to realize new Floquet topological phases(5-7) in two-dimensional TMDs.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据