Unconventional Flat Chern Bands and Preformed 2e Charges in Skyrmionic Moiré Superlattices*

The interplay of topological characteristics in real space and reciprocal space can lead to the emergence of unconventional topological phases. In this talk, 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 |C| = 2 dispersionless electronic bands when the skyrmion periodicity and the moir ́e periodicity are matched. Following the Wilczek argument, the statistics of the charge-carrying excitations in this case is bosonic, characterized by electronic charge Q = 2e, that is even in units of electron charge e. The required skyrmion coupling strength triggering the topological phase transition is realistic, with its threshold estimated as low as 4 meV. The Hofstadter butterfly spectrum of this phase is different resulting in an unexpected quantum Hall conductance sequence.