2018/12/10 by Kangjun Seo, Valeri N. Kotov, Bruno Uchoa · 1 citation
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.122.246402
published as Phys. Rev. Lett. 122, 246402 (2019) · 6 pages, 3 figures, supplementary material
arxiv created 2018/12/10 · arxiv updated 2019/06/24
We address the effective tight-binding Hamiltonian that describes the insulating Mott state of twisted graphene bilayers at a magic angle. In that configuration, twisted bilayers form a honeycomb superlattice of localized states, characterized by the appearance of flat bands with four-fold degeneracy. After calculating the maximally localized superlattice Wannier wavefunctions, we derive the effective spin model that describes the Mott state. We suggest that the system is an exotic ferromagnetic Mott insulator, with well defined experimental signatures.