Van der Waals heterostructures formed by two different monolayer semiconductors have emerged as a promising platform for new optoelectronic and spin/valleytronic applications. In addition to its atomically thin nature, a two-dimensional semiconductor heterostructure is distinct from its three-dimensional counterparts due to the unique coupled spin-valley physics of its constituent monolayers. Here, we report the direct observation that an optically generated spin-valley polarization in one monolayer can be transferred between layers of a two-dimensional MoSe2-WSe2 heterostructure. Using nondegenerate optical circular dichroism spectroscopy, we show that charge transfer between two monolayers conserves spin-valley polarization and is only weakly dependent on the twist angle between layers. Our work points to a new spin-valley pumping scheme in nanoscale devices, provides a fundamental understanding of spin-valley transfer across the two-dimensional interface, and shows the potential use of two-dimensional semiconductors as a spin-valley generator in 2D spin/valleytronic devices for storing and processing information.
@article{arxiv.1612.04863,
title = {Directional Interlayer Spin-Valley Transfer in Two-Dimensional Heterostructures},
author = {John R. Schaibley and Pasqual Rivera and Hongyi Yu and Kyle L. Seyler and Jiaqiang Yan and David G. Mandrus and Takashi Taniguchi and Kenji Watanabe and Wang Yao and Xiaodong Xu},
journal= {arXiv preprint arXiv:1612.04863},
year = {2017}
}