Direct evidence of interaction-induced Dirac cones in a monolayer silicene/Ag(111) system

Silicene, analogous to graphene, is a one-atom-thick 2D crystal of silicon, which is expected to share many of the remarkable properties of graphene. The buckled honeycomb structure of silicene, along with enhanced spin-orbit coupling, endows silicene with considerable advantages over graphene in th...

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Published in:Proceedings of the National Academy of Sciences - PNAS 2016-12, Vol.113 (51), p.14656-14661
Main Authors: Feng, Ya, Liu, Defa, Feng, Baojie, Liu, Xu, Zhao, Lin, Xie, Zhuojin, Liu, Yan, Liang, Aiji, Hu, Cheng, Hu, Yong, He, Shaolong, Liu, Guodong, Zhang, Jun, Chen, Chuangtian, Xu, Zuyan, Chen, Lan, Wu, Kehui, Liu, Yu-Tzu, Lin, Hsin, Huang, Zhi-Quan, Hsu, Chia-Hsiu, Chuang, Feng-Chuan, Bansil, Arun, Zhou, X. J.
Format: Article
Language:English
Subjects:
Carbon
catalysis (heterogeneous)
defects
Dirac cone
Electron transfer
energy storage (including batteries and capacitors)
hydrogen and fuel cells
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
interaction
materials and chemistry by design
MATERIALS SCIENCE
mechanical behavior
photoemission
Physical Sciences
Quantum physics
silicene
Silicon
solar (photovoltaic)
Substrates
synthesis (novel materials)
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Summary:Silicene, analogous to graphene, is a one-atom-thick 2D crystal of silicon, which is expected to share many of the remarkable properties of graphene. The buckled honeycomb structure of silicene, along with enhanced spin-orbit coupling, endows silicene with considerable advantages over graphene in that the spin-split states in silicene are tunable with external fields. Although the low-energy Dirac cone states lie at the heart of all novel quantum phenomena in a pristine sheet of silicene, a hotly debated question is whether these key states can survive when silicene is grown or supported on a substrate. Here we report our direct observation of Dirac cones in monolayer silicene grown on a Ag(111) substrate. By performing angle-resolved photoemission measurements on silicene(3 × 3)/Ag(111), we reveal the presence of six pairs of Dirac cones located on the edges of the first Brillouin zone of Ag(111), which is in sharp contrast to the expected six Dirac cones centered at the K points of the primary silicene(1 × 1) Brillouin zone. Our analysis shows clearly that the unusual Dirac cone structure we have observed is not tied to pristine silicene alone but originates from the combined effects of silicene(3 × 3) and the Ag(111) substrate. Our study thus identifies the case of a unique type of Dirac cone generated through the interaction of two different constituents. The observation of Dirac cones in silicene/Ag(111) opens a unique materials platform for investigating unusual quantum phenomena and for applications based on 2D silicon systems.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1613434114