Valley-chiral quantum Hall state in graphene superlattice structure H. Y. Tian, W. W. Tao, J. Wang, Y. H. Cui, N. Xu, B. B. Huang, G. X. Luo and Y. H. Hao EPL, 114 4 (2016) 47003 Published online: 14 June 2016 DOI: 10.1209/0295-5075/114/47003