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Cha, Soon Young
원자제어 저차원 전자계 연구단
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Ultrafast non-excitonic valley Hall effect in MoS2/WTe2 heterobilayers

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Title
Ultrafast non-excitonic valley Hall effect in MoS2/WTe2 heterobilayers
Author(s)
Lee, Jekwan; Heo, Wonhyeok; Cha, Myungjun; Watanabe, Kenji; Taniguchi, Takashi; Kim, Jehyun; Soonyoung Cha; Kim, Dohun; Moon-Ho Jo; Choi, Hyunyong
Publication Date
2021-03-12
Journal
NATURE COMMUNICATIONS, v.12, no.1
Publisher
NATURE RESEARCH
Abstract
The valley Hall effect (VHE) in two-dimensional (2D) van der Waals (vdW) crystals is a promising approach to study the valley pseudospin. Most experiments so far have used bound electron-hole pairs (excitons) through local photoexcitation. However, the valley depolarization of such excitons is fast, so that several challenges remain to be resolved. We address this issue by exploiting a unipolar VHE using a heterobilayer made of monolayer MoS2/WTe2 to exhibit a long valley-polarized lifetime due to the absence of electron-hole exchange interaction. The unipolar VHE is manifested by reduced photoluminescence at the MoS2 A exciton energy. Furthermore, we provide quantitative information on the time-dependent valley Hall dynamics by performing the spatially-resolved ultrafast Kerr-rotation microscopy; we find that the valley-polarized electrons persist for more than 4 nanoseconds and the valley Hall mobility exceeds 4.49x10(3)cm(2)/Vs, which is orders of magnitude larger than previous reports. The valley Hall effect in 2D materials is a promising approach for future valleytronic applications, but it is usually based on excitons with short lifetimes. Here, spin polarized electrons are injected from WTe2 into MoS2, leading to a unipolar valley Hall effect with enhanced lifetimes and mobility.
URI
https://pr.ibs.re.kr/handle/8788114/9474
DOI
10.1038/s41467-021-21013-w
ISSN
2041-1723
Appears in Collections:
Center for Artificial Low Dimensional Electronic Systems(원자제어 저차원 전자계 연구단) > 1. Journal Papers (저널논문)
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