Directional Interlayer Spin-Valley Transfer in Two-Dimensional Heterostructures

TL;DR

This paper demonstrates that spin-valley polarization can be transferred between layers in a 2D heterostructure, revealing a new mechanism for spin-valley control in nanoscale devices, with implications for optoelectronic and spintronic applications.

Contribution

It provides the first direct observation of spin-valley polarization transfer across a 2D heterostructure, highlighting a new spin-valley pumping mechanism independent of twist angle.

Findings

Charge transfer conserves spin-valley polarization

Transfer is weakly dependent on twist angle

Potential for 2D spin/valleytronic device applications

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 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.