Direct measurement of exciton valley coherence in monolayer WSe2
By Kai Hao, G. Moody, Fengcheng Wu, C. Dass, Lixiang Xu, Chang-Hsiao Chen, Liuyang Sun, Ming-Yang Li, Lain‐Jong Li, Allan H. MacDonald and 1 more. Nature Physics, 2015
288 citations recorded by the source corpus.
Coherent valley exciton dynamics are directly probed in a monolayer transition metal dichalcogenide, providing access to the valley coherence time and decoherence mechanisms — crucial for developing methods for manipulating the valley pseudospin. In crystals, energy band extrema in momentum space can be identified by a valley index. The internal quantum degree of freedom associated with valley pseudospin indices can act as a useful information carrier, analogous to electronic charge or spin1,2,3,4. Interest in valleytronics has been revived in recent years following the discovery of atomically thin materials such as graphene and transition metal dichalcogenides5,6,7. However, the valley coherence time—a crucial quantity for valley pseudospin manipulation—is difficult to directly probe. In this work, we use two-dimensional coherent spectroscopy to resonantly generate and detect valley coherence of excitons (Coulomb-bound electron–hole pairs) in monolayer WSe2 (refs 8,9). The imposed valley coherence persists for approximately one hundred femtoseconds. We propose that the electron–hole exchange interaction provides an important decoherence mechanism in addition to exciton population recombination. This work provides critical insight into the requirements and strategies for optical manipulation of the valley pseudospin for future valleytronics applications.
Subfields: Electrical and Electronic Engineering, Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/420bb63ff2812a4f7004f4a2e73a1d08588e843e
How researchers see this paper
The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.
In Electrical and Electronic Engineering
In Materials Chemistry
Citations in the corpus
- Optical properties of atomically thin transition metal dichalcogenides: observations and puzzles (2016, methodology): “Such experiments established S-TMDs as a possible platform for opto-valleytronic devices and led to the observation of valley coherence [100, 111].”