Abstract
Van der Waals heterostructures of transition metal dichalcogenides with interlayer coupling offer an exotic platform to realize fascinating phenomena. Due to the type II band alignment of these heterostructures, electrons and holes are separated into different layers. The localized electrons induced doping in one layer, in principle, would lift the Fermi level to cross the spin-polarized upper conduction band and lead to strong manipulation of valley magnetic response. Here, we report the significantly enhanced valley Zeeman splitting and magnetic tuning of polarization for the direct optical transition of MoS2 in MoS2/WS2 heterostructures. Such strong enhancement of valley magnetic response in MoS2 stems from the change of the spin-valley degeneracy from 2 to 4 and strong many-body Coulomb interactions induced by ultrafast charge transfer. Moreover, the magnetic splitting can be tuned monotonically by laser power, providing an effective all-optical route towards engineering and manipulating of valleytronic devices and quantum-computation.
Highlights
Van der Waals heterostructures of transition metal dichalcogenides with interlayer coupling offer an exotic platform to realize fascinating phenomena
The valley degeneracy in transition metal dichalcogenides (TMDCs) has been lifted via applying an external magnetic field, which is known as the valley Zeeman effect and plays a prominent role to manipulate valley polarization and valley coherence for logic valleytronic devices[18,19,20,21,22,23,24,25,26]
The profile is dominated by the intralayer exciton of both monolayers with PL intensity quench by a factor of 50 (100) compared with MoS2 (WS2) which is attributed to efficient interlayer charge transfer between layers[41,42]
Summary
Van der Waals heterostructures of transition metal dichalcogenides with interlayer coupling offer an exotic platform to realize fascinating phenomena. In close analogy to electrostatic doping, ultrafast charge transfer in hetero-bilayers of TMDCs with type II band alignments, e.g., MoS2/WS2 heterostructures, generates electrons and holes separated in different layers and gives rise to the n-doping (p-doping) for MoS2 (WS2)[41,42]. Such ultrafast charge transfer induced doping would strengthen the Coulomb exchange interactions, leading to the strongly enhanced valley splitting and susceptibility. Our results will stimulate the widespread development in general doping enhanced magnetic susceptibility of 2D electron gas system in van der Waals (vdW) heterostructures
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