Magnetic-gateable valley exciton emission

• Published in: npj computational materials Vol. 6; no. 1
• Main Authors: Bragança, Helena, Zeng, Hao, Dias, Alexandre Cavalheiro, Correa, Jorge Huamani, Qu, Fanyao
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 07.07.2020; Nature Publishing Group
• Subjects: 639/766/25; 639/925/357/1018; Brightening; Carrier recombination; Characterization and Evaluation of Materials; Chemistry and Materials Science; Computational Intelligence; Data processing; Emission; Exchanging; Excitons; Information processing; Materials Science; Mathematical and Computational Engineering; Mathematical and Computational Physics; Mathematical Modeling and Industrial Mathematics; Molybdenum disulfide; Polarization; Polarization (spin alignment); Proximity effect (electricity); Recombination; Room temperature; Theoretical; Transition metal compounds; Valleys
• ISSN: 2057-3960; 2057-3960
• DOI: 10.1038/s41524-020-00356-w

The use of valley excitonic states of transition metal dichalcogenides to store and manipulate information is hampered by fast carrier recombination and short valley lifetime. We propose theoretically a scheme to overcome such an obstacle, by applying a tilted exchange field through the magnetic proximity effect on monolayer MoS 2 . While the in-plane component of the exchange field brightens the dark exciton by spin mixing, the out-of-plane field can effectively gate the emission with an ON/OFF ratio of 2700. Importantly, the brightening is valley selective, leading to nearly 100% valley and spin polarization at room temperature. The resulting strongly gateable dark-exciton emission with long lifetime and near unity valley polarization makes it convenient to manipulate the valley degree of freedom, which may offer new paradigm for information processing and transmission.