Magic Angle Hierarchy in Twisted Graphene MultilayersAugust 7, 2019
A schematic illustration of the alternating-twist multilayer graphene: Trilayer (left) and quadrilayer (right).
The recent discovery of correlated insulating states and superconductivity in twisted bilayer graphene has opened the door to a new approach to designing correlated materials by controlling the twist angles. In a new study published in Physical Revew B, researchers in Prof. Ashvin Vishwanath group propose a large class of graphene-based moiré heterostructures which similarly exhibit flat bands at a sequence of magic angles whose pattern is analytically related to the bilayer magic angles. This setup may be experimentally more stable compared to the bilayer case and features the coexistence of a flat band with Dirac dispersing bands, potentially leading to qualitatively different types of flat-band induced correlated phases.
Read Eslam Khalaf, Alex J. Kruchkov, Grigory Tarnopolsky, and Ashvin Vishwanath, Phys. Rev. B 100 (2019) https://doi.org/10.1103/PhysRevB.100.085109.