Chunlong Wu, Qiang Wan, Cao Peng, Shangkun Mo, Renzhe Li, Keming Zhao, Yanping Guo, Shengjun Yuan, Fengcheng Wu, Chendong Zhang, and Nan Xu.Phys. Rev. Lett.（徐楠）
We report an experimental study of a high-order moiré pattern formed in graphene-monolayer xenon heterostructure. The moiré period is in situ tuned from few nanometers to +∞, by adjusting the lattice constant of the xenon monolayer through annealing. Using angle-resolved photoemission spectroscopy, we observe that Dirac node replicas move closer and finally overlap with a gap opening, as the moiré pattern expands to +∞ and evolves into a Kekulé distortion. A moiré Hamiltonian coupling Dirac fermions from different valleys explains experimental results and indicates narrow moiré band. Our Letter demonstrates a platform to study continuous evolution of the moiré pattern, and provides an unprecedented approach for tailoring Dirac fermions with tunable intervalley coupling.