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dc.contributor.authorHao, Kai
dc.contributor.authorMoody, Galan
dc.contributor.authorWu, Fengcheng
dc.contributor.authorDass, Chandriker Kavir
dc.contributor.authorXu, Lixiang
dc.contributor.authorChen, Chang Hsiao
dc.contributor.authorSun, Liuyang
dc.contributor.authorLi, Ming-yang
dc.contributor.authorLi, Lain-Jong
dc.contributor.authorMacDonald, Allan H.
dc.contributor.authorLi, Xiaoqin
dc.date.accessioned2017-01-02T09:28:28Z
dc.date.available2017-01-02T09:28:28Z
dc.date.issued2016-02-29
dc.identifier.citationHao K, Moody G, Wu F, Dass CK, Xu L, et al. (2016) Direct measurement of exciton valley coherence in monolayer WSe2. Nature Physics 12: 677–682. Available: http://dx.doi.org/10.1038/nphys3674.
dc.identifier.issn1745-2473
dc.identifier.issn1745-2481
dc.identifier.doi10.1038/nphys3674
dc.identifier.urihttp://hdl.handle.net/10754/622388
dc.description.abstract<p>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 spin. Interest in valleytronics has been revived in recent years following the discovery of atomically thin materials such as graphene and transition metal dichalcogenides. 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 WSe<sub>2</sub> (refs <span></span>,<span></span>). 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.</p>
dc.description.sponsorshipThe theoretical and experimental collaboration is made possible by SHINES, an Energy Frontier Research Center funded by the US Derailment of Energy (DoE), Office of Science, Basic Energy-Science (BES) under award # DE-SC0012070. K.H., F.W., L.X., X.L. and A.H.M. have all received support from SHINES. Optical spectroscopy studies performed by K.H., C.K.D., L.S. and X.L. have been partially supported by NSF DMR-1306878 and Welch Foundation F-1662. A.H.M. also acknowledges support from Welch Foundation F-1473. L.J.L. is grateful for support from KAUST Saudi Arabia, Academia Sinica Taiwan, and AOARD FA23861510001 USA. C.-H.C. is grateful for support from the Ministry of Science and Technology Taiwan (MOST 104-2218-E-035-010 and 104-2628-E-035-002-MY3).
dc.publisherSpringer Nature
dc.subjectElectronic properties and materials
dc.subjectTwo-dimensional materials
dc.subjectQuantum mechanics
dc.subjectNear-infrared spectroscopy
dc.titleDirect measurement of exciton valley coherence in monolayer WSe2
dc.typeArticle
dc.contributor.departmentMaterials Science and Engineering Program
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Division
dc.identifier.journalNature Physics
dc.contributor.institutionDepartment of Physics, Center for Complex Quantum Systems, University of Texas at Austin, Austin, TX, 78712, United States
dc.contributor.institutionNational Institute of Standards and Technology, Boulder, CO, 80305, United States
dc.contributor.institutionDepartment of Automatic Control Engineering, Feng Chia University, Taichung, 40724, Taiwan
dc.identifier.arxividarXiv:1509.08810
kaust.personLi, Ming-yang
kaust.personLi, Lain-Jong
dc.date.published-online2016-02-29
dc.date.published-print2016-07


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