Electric field mediated large valley splitting in the van der Waals heterostructure WSe2/CrI3

In contrast to commonly used means such as the magnetic field, here an electric field is used to achieve a large valley splitting in the van der Waals (vdW) heterostructure WSe2/CrI3. CrI3 contributes to the spin moment. The electric field pushes the valence bands of Cr atoms close to those of the W atoms associated with pseudospin so that they can interact through the exchange interaction. The opposite helicities of pseudospin at the K and K' points realize a valley splitting as large as 10.5 meV under an electric field of 0.1 V A−1. The underlying physics stems from the interlayer charge transfer, where the spin conservation plays a role.