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The interplay of topological characteristics in real space and reciprocal space can lead to the emergence of unconventional topological phases. In this Letter, we implement a novel mechanism for generating higher-Chern flat bands on the basis of twisted bilayer graphene (TBG) coupled to topological magnetic structures in the form of the skyrmion lattice. In particular, we discover a scenario for generating vertical bar C vertical bar = 2 dispersionless electronic bands when the skyrmion periodicity and the moire ' periodicity match. Following the Wilczek argument, the statistics of the charge-carrying excitations in this case is bosonic, characterized by electronic charge Q = 2e, which is even in units of electron charge e. The skyrmion coupling strength triggering the topological phase transition is realistic, with its lower bound estimated as 4 meV. The Hofstadter butterfly spectrum results in an unexpected quantum Hall conductance sequence +/- 2e(2)/h, +/- 4e(2)/h, ... for TBG with the skyrmion order.
Klaus Kern, Marko Burghard, Lukas Powalla
Benoît Guilhem Michel Binh Truc