24 August 2018
Vol 361, Issue 6404

About The Cover

Cover image expansion

COVER Quasi-periodic tiling arises from bilayer graphene. Relativistic electrons called Dirac electrons are realized on a quasicrystal prepared by depositing one atomically thin carbon layer atop another at a 30° twist angle. Three basic building blocks—squares, rhombuses, and equilateral triangles—with different orientations can fill the entire space of the 12-fold rotationally symmetric quasicrystal without translational symmetry. See page 782. For more on the process behind the cover image, see
Illustration: V. Altounian/Science; Code: P. Stampfli