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

Ya Feng, De-Fa Liu, B. Feng, Xu Liu, Lin Zhao, Zhuojin Xie, Yan Liu, Ai-Ji Liang et al.

Proceedings of the National Academy of Sciences of the United States of America, 2015

68 citations

Abstract

Significance Silicene is a one-atom-thick 2D crystal of silicon. The low-energy Dirac cone states in silicene lie at the heart of all novel quantum phenomena and potential applications. However, so far, the evidence of Dirac cones in silicene is highly controversial. We report a direct observation of Dirac cones in monolayer silicene grown on a Ag(111) substrate. We further show that this unusual Dirac cone structure originates from the interaction of silicene with the Ag(111) substrate, establishing the case of a unique type of Dirac fermion generated through the interaction of two different constituents. The observation of Dirac cones in silicene(3 × 3)/Ag(111) opens a unique materials platform for investigating unusual quantum phenomena and for applications based on 2D silicon systems. 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…

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