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Room‐Temperature Active Modulation of Valley Dynamics in a Monolayer Semiconductor through Chiral Purcell Effects
Author(s) -
Wu Zilong,
Li Jingang,
Zhang Xiaotian,
Redwing Joan M.,
Zheng Yuebing
Publication year - 2019
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201904132
Subject(s) - monolayer , materials science , exciton , metamaterial , semiconductor , plasmon , dielectric , polarization (electrochemistry) , purcell effect , optoelectronics , modulation (music) , circular polarization , active layer , condensed matter physics , nanotechnology , spontaneous emission , optics , physics , layer (electronics) , chemistry , laser , thin film transistor , acoustics , microstrip
Spin‐dependent contrasting phenomena at K and K ′ valleys in monolayer semiconductors have led to addressable valley degree of freedom, which is the cornerstone for emerging valleytronic applications in information storage and processing. Tunable and active modulation of valley dynamics in a monolayer WSe 2 is demonstrated at room temperature through controllable chiral Purcell effects in plasmonic chiral metamaterials. The strong spin‐dependent modulation on the spontaneous decay of valley excitons leads to tunable handedness and spectral shift of valley‐polarized emission, which is analyzed and predicted by an advanced theoretical model and further confirmed by experimental measurements. Moreover, large active spectral tuning (≈24 nm) and reversible ON/OFF switching of circular polarization of emission are achieved by the solvent‐controllable thickness of the dielectric spacer in the metamaterials. With the on‐demand and active tunability in valley‐polarized emission, chiral Purcell effects can provide new strategies to harness valley excitons for applications in ultrathin valleytronic devices.