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Magic-angle semimetals
Physicsnpj Quantum Materials

Magic-angle semimetals

Y. Fu, E. J. König, et al.

Explore the groundbreaking realm of magic-angle semimetals, where twisting in two-dimensional van der Waals heterostructures leads to incredible phenomena such as flat bands and multifractal wave functions. This research, conducted by Yixing Fu, Elio J. König, Justin H. Wilson, Yang-Zhi Chou, and Jedediah H. Pixley, unlocks new observational possibilities across various systems.... show more
Abstract
Breakthroughs in two-dimensional van der Waals heterostructures have revealed that twisting creates a moiré 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.
Publisher
npj Quantum Materials
Published On
Oct 06, 2020
Authors
Yixing Fu, Elio J. König, Justin H. Wilson, Yang-Zhi Chou, Jedediah H. Pixley
Tags
magic-angle semimetalsquantum phase transitiontwistingflat bandsmultifractal wave functionsultracold Fermi gasesmetamaterials
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