Manipulating the valley degree of freedom of transition metal dichalcogenides via van der Waals magnetic tunnel junctions

The monolayer transition metal dichalcogenides (TMDs) are ideal candidates for future valleytronics applications owing to the unique spin valley locking properties and valley-dependent optical selection rule. Over the past few years, several works have shown the possibility of manipulating the valley degree of freedom of TMDs using circularly polarized light. But to electrically control the valley-dependent polarization remains a critical challenge. In this talk, we demonstrate that Fe₃GeTe₂ (FGT)-based tunneling contact can effectively inject spin-polarized holes into the specific valley of monolayer TMD. This importantly gives rise to valley-dependent polarization as confirmed by our helicity-dependent electroluminescence and reflective magnetic circular dichroism (RMCD) measurements. Moreover, our density functional theory calculations reveal that FGT owns the strong exchange splitting of spin bands at point K in its Brillouin zone, which enables the efficient injection of spin-polarized carriers. Our results not only provide further insight into FGT, but also address challenges of valleytronics.