Van der Waals Engineering of Ferromagnetic Semiconductor Heterostructures for Spin and Valleytronics

TL;DR

This paper demonstrates the creation of van der Waals heterostructures combining ferromagnetic CrI3 and WSe2, enabling control of spin and valley pseudospin with large exchange fields and ultrafast switching, advancing spintronics and valleytronics.

Contribution

It introduces a novel heterostructure platform that allows for unprecedented control of spin and valley pseudospin in 2D materials through magnetic exchange interactions.

Findings

Large magnetic exchange field of nearly 13 T detected.

Rapid switching of valley splitting and polarization via magnetization flipping.

Photoluminescence intensity depends on spin alignment, revealing ultrafast spin-dependent charge hopping.

Abstract

The integration of magnetic material with semiconductors has been fertile ground for fundamental science as well as of great practical interest toward the seamless integration of information processing and storage. Here we create van der Waals heterostructures formed by an ultrathin ferromagnetic semiconductor CrI3 and a monolayer of WSe2. We observe unprecedented control of the spin and valley pseudospin in WSe2, where we detect a large magnetic exchange field of nearly 13 T and rapid switching of the WSe2 valley splitting and polarization via flipping of the CrI3 magnetization. The WSe2 photoluminescence intensity strongly depends on the relative alignment between photo-excited spins in WSe2 and the CrI3 magnetization, due to ultrafast spin-dependent charge hopping across the heterostructure interface. The photoluminescence detection of valley pseudospin provides a simple and sensitive method to probe the intriguing domain dynamics in the ultrathin magnet, as well as the rich spin interactions within the heterostructure.