Valley-Dependent Interlayer Excitons in Magnetic WSe2/CrI3

Heterostructures of two-dimensional transition-metal dichal-cogenides and ferromagnetic substrates are important candidates for the development of viable new spin- or valleytronic devices. For the prototypical bilayer of WSe2 on top of a ferromagnetic layer of CrI3, we find substantially different coupling of both WSe2 K-valleys to the sublayer. Besides an energy splitting of a few meV, the corresponding excitons have significantly different interlayer character with charge transfer allowed at the (K) over bar (-) point but forbidden at (K) over bar (-). The different exciton wave functions result in a distinctly different response to magnetic fields with g factors of about -4.4 and -4.0, respectively. By means of ab initio GW/Bethe-Salpeter equation calculations, these findings establish g factors as tool for investigating the exciton character and shedding light on the detailed quantummechanical interplay of magnetic and optical properties which are essential for the targeted development of optoelectronic devices.

Automated summary

Heterostructures of two-dimensional transition-metal dichalcogenides and ferromagnetic substrates show different coupling and exciton wave functions, resulting in varied responses to magnetic fields. The findings suggest g factors as a tool for investigating exciton characteristics and shedding light on the quantummechanical interplay of magnetic and optical properties.