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dc.contributor.authorWang, Yanlongen_US
dc.contributor.authorCong, Chunxiaoen_US
dc.contributor.authorShang, Jingzhien_US
dc.contributor.authorEginligil, Mustafaen_US
dc.contributor.authorJin, Yuqien_US
dc.contributor.authorLi, Gangen_US
dc.contributor.authorChen, Yuen_US
dc.contributor.authorPeimyoo, Namphungen_US
dc.contributor.authorYu, Tingen_US
dc.identifier.citationWang, Y., Cong, C., Shang, J., Eginligil, M., Jin, Y., Li, G., ... Yu, T. (2019). Unveiling exceptionally robust valley contrast in AA- and AB-stacked bilayer WS2. Nanoscale Horizons, 4(2), 396-403. doi:10.1039/C8NH00306Hen_US
dc.description.abstractValleytronics is a particularly interesting field that employs the valley degree of freedom for information manipulation. The fascinating prospects for realizing valleytronic devices have inspired persistent efforts towards exploring material systems with robust valley polarization. Monolayer transition metal dichalcogenides (TMDs) obey the well-known valley-dependent selection rule as a result of their inversion asymmetry. However, for inversionsymmetric bilayer tungsten-based TMDs, highly selective valley polarization has been surprisingly observed and is not yet fully understood. Here we systematically study the origin of the anomalously high valley polarization in bilayer WS2 by temperaturedependent polarization-resolved photoluminescence measurements. It is found that acoustic phonons play a critical role in the valley polarization of bilayer WS2. For some WS2 bilayers with relatively small intensity ratios of indirect to direct bandgap emission, acoustic phonons could remarkably assist the intervalley scattering process and smear the valley contrast. On the other hand, in other bilayers, which show obvious indirect band gap emission, the indirect optical transition process depletes the phonon mode at the K point dramatically and results in anomalously robust valley polarization in bilayer WS2. These results help recognize the crucial role of electron–phonon coupling in intervalley relaxation in bilayer WS2 and provide new insights into the future design of valleytronic devices based on two-dimensional TMDs.en_US
dc.description.sponsorshipMinistry of Education (MOE)en_US
dc.relation.ispartofNanoscale Horizonsen_US
dc.rights© 2018 Royal Society of Chemistry. All rights reserved. This paper was published in Nanoscale Horizons and is made available with permission of Royal Society of Chemistry.en_US
dc.titleUnveiling exceptionally robust valley contrast in AA- and AB-stacked bilayer WS2en_US
dc.typeJournal Articleen
dc.contributor.schoolSchool of Physical and Mathematical Sciencesen_US
dc.description.versionAccepted versionen_US
dc.description.acknowledgementThis work was supported by the National Natural Science Foundation of China (No. 61774040 and 11774170), Ministry of Education (MOE) Tier 1 RG199/17, the National Young 1000 Talent Plan of China, the Shanghai Municipal Natural Science Foundation (No. 16ZR1402500), the Opening project of the State Key Laboratory of Functional Materials for Informatics, the Shanghai Institute of Microsystem and Information Technology, the Chinese Academy of Sciences, the China Postdoctoral Science Foundation (Grant 2018M631829), the dedicated grant for methanol conversion from DICP, the Six Talent Peaks project in Jiangsu Province under grant number 51235079, and the 100 Foreign Talents Project in Jiangsu Province under grant number 51235228en_US
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