This may satisfy certain application requirements for topological heterostructures and graphene-related electronic devices. Acknowledgements This work was financially supported by projects from the Natural Science Foundation of China (Grant Nos. 11104303, 11274333, 11204339, 61136005, and 50902150), Chinese Academy of Sciences (Grant Nos. KGZD-EW-303, XDA02040000, and XDB04010500), the Open Foundation of State Key Laboratory of Functional Materials for Informatics (Grant No. SKL201309), the National High-tech R

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