期刊
ACS NANO
卷 16, 期 5, 页码 8064-8075出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.2c01065
关键词
high pressure; TMDs; strain; double-resonance Raman; multivalley physics
类别
资金
- MURI Project by the U.S. Army Research Office (ARO) [W911NF-18-1-0431]
- CNPq [206251/2014-9]
- National Science Foundation under NSF [1541959]
- CAPES
- Fapemig
- INCT-Nano-Carbono
- UFOP
- Center for Information Technology of the University of Groningen
- CNPq
Transition metal dichalcogenides exhibit interesting physical phenomena, but the multivalley effects are hindered in monolayers. By using high pressure, the electronic properties of monolayer MoS2 and WSe2 can be tuned, enabling sensitive probing of multivalley phenomena.
Transition metal dichalcogenides (TMDs) possess spin-valley locking and spin-split K/K' valleys, which have led to many fascinating physical phenomena. However, the electronic structure of TMDs also exhibits other conduction band minima with similar properties, the Q/Q' valleys. The intervalley K-Q scattering enables interesting physical phenomena, including multivalley superconductivity, but those effects are typically hindered in monolayer TMDs due to the large K-Q energy difference (Delta E-KQ). To unlock elusive multivalley phenomena in monolayer TMDs, it is desirable to reduce Delta E-KQ, while being able to sensitively probe the valley shifts and the multivalley scattering processes. Here, we use high pressure to tune the electronic properties of monolayer MoS2 and WSe2 and probe K-Q crossing and multivalley scattering via double-resonance Raman (DRR) scattering. In both systems, we observed a pressure-induced enhancement of the double-resonance LA and 2LA Raman bands, which can be attributed to a band gap opening and Delta E-KQ decrease. First-principles calculations and photoluminescence measurements corroborate this scenario. In our analysis, we also addressed the multivalley nature of the DRR bands for WSe2. Our work establishes the DRR 2LA and LA bands as sensitive probes of strain-induced modifications to the electronic structure of TMDs. Conversely, their intensity could potentially be used to monitor the presence of compressive or tensile strain in TMDs. Furthermore, the ability to probe K-K' and K-Q scattering as a function of strain shall advance our understanding of different multivalley phenomena in TMDs such as superconductivity, valley coherence, and valley transport.
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