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Magic-angle semimetals

TitleMagic-angle semimetals
Publication TypeJournal Article
Year of Publication2020
AuthorsY. Fu, E. J. Konig, J. H. Wilson, Y-Z. Chou, and J. H. Pixley
Journalnpj Quantum Mater.
Date PublishedOCT 6
Type of ArticleArticle

Breakthroughs in two-dimensional van der Waals heterostructures have revealed that twisting creates a moire pattern that quenches the kinetic energy of electrons, allowing for exotic many-body states. We show that cold atomic, trapped ion, and metamaterial systems can emulate the effects of a twist in many models from one to three dimensions. Further, we demonstrate at larger angles (and argue at smaller angles) that by considering incommensurate effects, the magic-angle effect becomes a single-particle quantum phase transition (including in a model for twisted bilayer graphene in the chiral limit). We call these models ``magic-angle semimetals{''}. Each contains nodes in the band structure and an incommensurate modulation. At magic-angle criticality, we report a nonanalytic density of states, flat bands, multifractal wave functions that Anderson delocalize in momentum space, and an essentially divergent effective interaction scale. As a particular example, we discuss how to observe this effect in an ultracold Fermi gas.