Twist-angle-controlled magnetopolarization switching in a WS₂/WSe₂ heterostructure

Van der Waals heterostructures of transition metal dichalcogenides offer a versatile platform for valleytronic applications, owing to their spin-valley locking and layer-dependent optical selection rules. Here, we demonstrate the twist-angle-controlled helicity switching of interlayer exciton (IX) emission by showing that the polarizations of the IX photoluminescence can be engineered by altering the stacking geometry of WS₂/WSe₂ heterobilayers. It is also found that a sufficiently large (∼5 T) out-of-plane magnetic field can enhance the polarization degree of the IX emission up to ∼60%, which enables controlled valley population imbalance of the IXs. The findings establish twist angle as a control knob for IX helicity and highlight magnetic fields as an efficient means of reinforcing valley polarization, paving the way toward valley and twist-angle based optoelectronic devices.