Quenched Excitons in WSe₂/α-RuCl₃ Heterostructures Revealed by Multimessenger Nanoscopy

We investigate heterostructures composed of monolayer WSe₂ stacked on α-RuCl₃ using a combination of Terahertz (THz) and infrared (IR) nanospectroscopy and imaging, scanning tunneling spectroscopy (STS), and photoluminescence (PL). Our observations reveal itinerant carriers in the heterostructure prompted by charge transfer across the WSe₂/α-RuCl₃ interface. Local STS measurements show the Fermi level is shifted to the valence band edge of WSe₂ which is consistent with p-type doping and verified by density functional theory (DFT) calculations. We observe prominent resonances in near-IR nano-optical and PL spectra, which are associated with the A-exciton of WSe₂. We identify a concomitant, near total, quenching of the A-exciton resonance in the WSe₂/α-RuCl₃ heterostructure. Our nano-optical measurements show that the charge-transfer doping vanishes while excitonic resonances exhibit near-total recovery in "nanobubbles", where WSe₂ and α-RuCl₃ are separated by nanometer distances. Our broadband nanoinfrared inquiry elucidates local electrodynamics of excitons and an electron-hole plasma in the WSe₂/α-RuCl₃ system.