Valley-polarized exciton dynamics in a 2D semiconductor heterostructure

• Autores: Pasqual Rivera, Kyle L. Seyler, Hongyi Yu, John R. Schaibley
• Localización: Science, ISSN 0036-8075, Vol. 351, Nº 6274, 2016, págs. 688-691
• Idioma: inglés
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• Resumen

  • 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.