title: Valley-polarized exciton dynamics in a 2D semiconductor heterostructure.
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.
authors.affiliation: Department of Physics, University of Washington, Seattle, WA 98195, USA.
authors.forename: Pasqual
authors.initials: P
authors.lastname: Rivera
authors.affiliation: Department of Physics, University of Washington, Seattle, WA 98195, USA.
authors.forename: Kyle L
authors.initials: KL
authors.lastname: Seyler
authors.affiliation: Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong, China.
authors.forename: Hongyi
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Physics, University of Washington, Seattle, WA 98195, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Schaibley
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Jiaqiang
authors.initials: J
authors.lastname: Yan
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA. Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: David G
authors.initials: DG
authors.lastname: Mandrus
authors.affiliation: Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong, China.
authors.forename: Wang
authors.initials: W
authors.lastname: Yao
authors.affiliation: Department of Physics, University of Washington, Seattle, WA 98195, USA. Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195, USA. xuxd@uw.edu.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Xu