Electric field tunable valley-Zeeman effect in bilayer graphene heterostructure: realization of the spin-orbit valve effect

Heterostructures of graphene with transition metal dichalcogenides (TMDCs) offer a plethora of interesting electronic properties. The presence of layer degree of freedom in bilayer graphene (BLG) provides unprecedented control over layer polarization. Here, we establish the band-structure evolution from an interplay between proximity induced strong spin-orbit interaction (SOI) and the layer-polarizability in BLG/WSe2 heterostructure through magnetoconductance measurement. The effective valley-Zeeman SOI in this heterostructure can be switched on/off by applying a transverse displacement field or can be controllably transferred between the valence and the conduction band. This results in an evolution from weak localization to weak anti-localization at a constant electronic density as the net displacement field is tuned from a positive to negative a value with a concomitant SOI-induced splitting of the low-energy bands of the BLG near the K(K’)–valley which is a unique signature of the theoretically predicted spin-orbit valve effect. Our analysis shows that quantum correction to the Drude conductance in Dirac materials with strong induced SOI can only be explained satisfactorily by a theory which accounts for the SOI induced spin-splitting of the BLG low-energy bands