Directional interlayer spin-valley transfer in two-dimensional heterostructures.

Schaibley, John R; Rivera, Pasqual; Yu, Hongyi; Seyler, Kyle L; Yan, Jiaqiang; Mandrus, David G; Taniguchi, Takashi; Watanabe, Kenji et al. · Nat Commun · 2016

basic_science · Level V

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Abstract

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 MoSe<sub>2</sub>-WSe<sub>2</sub> heterostructure. Using non-degenerate 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 two-dimensional spin/valleytronic devices for storing and processing information.