Valley-polarized exciton dynamics in a 2D semiconductor heterostructure

Pasqual Rivera; Kyle L. Seyler; Hongyi Yu; John R. Schaibley; Jiaqiang Yan; David G. Mandrus; Wang Yao; Xiaodong Xu

doi:10.1126/science.aac7820

Valley-polarized exciton dynamics in a 2D semiconductor heterostructure

Pasqual Rivera, Kyle L. Seyler, Hongyi Yu, John R. Schaibley, Jiaqiang Yan, David G. Mandrus, Wang Yao, Xiaodong Xu

Correlated Electron Materials

Research output: Contribution to journal › Article › peer-review

654 Scopus citations

Abstract

Heterostructures comprising different monolayer semiconductors provide an attractive setting for fundamental science and device technologies, such as in the emerging field of valleytronics. We realized valley-specific interlayer excitons in monolayer WSe₂-MoSe₂ vertical heterostructures. We created interlayer exciton spin-valley polarization by means of circularly polarized optical pumping and determined a valley lifetime of 40 nanoseconds. This long-lived polarization enables the visualization of the expansion of a valley-polarized exciton cloud over several micrometers. The spatial pattern of the polarization evolves into a ring with increasing exciton density, a manifestation of valley exciton exchange interactions. Our work introduces van der Waals heterostructures as a promising platform from which to study valley exciton physics.

Original language	English
Pages (from-to)	688-691
Number of pages	4
Journal	Science
Volume	351
Issue number	6274
DOIs	https://doi.org/10.1126/science.aac7820
State	Published - Feb 12 2016

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abstract = "Heterostructures comprising different monolayer semiconductors provide an attractive setting for fundamental science and device technologies, such as in the emerging field of valleytronics. We realized valley-specific interlayer excitons in monolayer WSe2-MoSe2 vertical heterostructures. We created interlayer exciton spin-valley polarization by means of circularly polarized optical pumping and determined a valley lifetime of 40 nanoseconds. This long-lived polarization enables the visualization of the expansion of a valley-polarized exciton cloud over several micrometers. The spatial pattern of the polarization evolves into a ring with increasing exciton density, a manifestation of valley exciton exchange interactions. Our work introduces van der Waals heterostructures as a promising platform from which to study valley exciton physics.",

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AU - Rivera, Pasqual

AU - Seyler, Kyle L.

AU - Yu, Hongyi

AU - Schaibley, John R.

AU - Yan, Jiaqiang

AU - Mandrus, David G.

AU - Yao, Wang

AU - Xu, Xiaodong

PY - 2016/2/12

Y1 - 2016/2/12

N2 - Heterostructures comprising different monolayer semiconductors provide an attractive setting for fundamental science and device technologies, such as in the emerging field of valleytronics. We realized valley-specific interlayer excitons in monolayer WSe2-MoSe2 vertical heterostructures. We created interlayer exciton spin-valley polarization by means of circularly polarized optical pumping and determined a valley lifetime of 40 nanoseconds. This long-lived polarization enables the visualization of the expansion of a valley-polarized exciton cloud over several micrometers. The spatial pattern of the polarization evolves into a ring with increasing exciton density, a manifestation of valley exciton exchange interactions. Our work introduces van der Waals heterostructures as a promising platform from which to study valley exciton physics.

AB - Heterostructures comprising different monolayer semiconductors provide an attractive setting for fundamental science and device technologies, such as in the emerging field of valleytronics. We realized valley-specific interlayer excitons in monolayer WSe2-MoSe2 vertical heterostructures. We created interlayer exciton spin-valley polarization by means of circularly polarized optical pumping and determined a valley lifetime of 40 nanoseconds. This long-lived polarization enables the visualization of the expansion of a valley-polarized exciton cloud over several micrometers. The spatial pattern of the polarization evolves into a ring with increasing exciton density, a manifestation of valley exciton exchange interactions. Our work introduces van der Waals heterostructures as a promising platform from which to study valley exciton physics.

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Valley-polarized exciton dynamics in a 2D semiconductor heterostructure

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