Modulating spin-valley relaxation in WSe₂ with variable thickness VOPc layers

초록

Combining the synthetic tunability of molecular compounds with the optical selection rules of transition metal dichalcogenides (TMDCs) that derive from spin-valley coupling could provide interesting opportunities for the readout of quantum information. However, little is known about the electronic and spin interactions at such interfaces and the influence on spin-valley relaxation. In this work, vanadyl phthalocyanine (VOPc) molecular layers are thermally evaporated on WSe2 to explore the effect of molecular layer thickness on excited-state spin-valley polarization. The thinnest molecular layer supports an interfacial state which destroys the spin-valley polarization almost instantaneously, whereas a thicker molecular layer results in longer-lived spin-valley polarization than the WSe2 monolayer alone. The mechanism appears to involve a tightly bound species at the molecule/TMDC interface that strengthens exchange interactions and is largely avoided in thicker VOPc layers that isolate electrons from WSe2 holes.

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