Heterostructures comprising different monolayer semiconductors provide a new system for fundamental science and device technologies, such as in the emerging field of valleytronics. Here, we realize valley-specific interlayer excitons in monolayer WSe2-MoSe2 vertical heterostructures. We create interlayer exciton spin-valley polarization by circularly polarized optical pumping and determine a valley lifetime of 40 nanoseconds. This long-lived polarization enables the visualization of the expansion of a valley-polarized exciton cloud over several microns. The spatial pattern of the polarization evolves into a ring with increasing exciton density, a manifestation of valley exciton exchange interactions. Our work lays a foundation for quantum optoelectronics and valleytronics based on interlayer excitons in van der Waals heterostructures.
@article{arxiv.1601.02641,
title = {Expansion of a Valley-Polarized Exciton Cloud in a 2D Heterostructure},
author = {Pasqual Rivera and Kyle L. Seyler and Hongyi Yu and John R. Schaibley and Jiaqiang Yan and David G. Mandrus and Wang Yao and Xiaodong Xu},
journal= {arXiv preprint arXiv:1601.02641},
year = {2016}
}
Comments
This is the original submitted version. The final version is to appear in Science