Magicangle semimetals
Abstract
Breakthroughs in twodimensional van der Waals heterostructures have revealed that twisting creates a moiré pattern that quenches the kinetic energy of electrons, allowing for exotic manybody 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 magicangle effect becomes a singleparticle quantum phase transition (including in a model for twisted bilayer graphene in the chiral limit). We call these models "magicangle semimetals". Each contains nodes in the band structure and an incommensurate modulation. At magicangle 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.
 Publication:

npj Quantum Materials
 Pub Date:
 October 2020
 DOI:
 10.1038/s41535020002719
 arXiv:
 arXiv:1809.04604
 Bibcode:
 2020npjQM...5...71F
 Keywords:

 Condensed Matter  Strongly Correlated Electrons;
 Condensed Matter  Disordered Systems and Neural Networks;
 Condensed Matter  Quantum Gases
 EPrint:
 8 pages, 5 figures and supplemental material