Superconductivity is a state that exhibits quantum behavior macroscopically, allowing electric currents to circulate indefinitely without any resistance whatsoever. The large moiré pattern of the superlattice is both visually striking and electrically special, as the emergence of superconductivity shows. This large hexagonal superlattice enables large numbers of electrons to interact, with interesting results, especially when the layers are rotated at specific angles at which, apparently, quantum tunneling can occur. The second layer is slightly rotated, and the skewed overlap between the two creates a larger hexagonal moiré pattern (outlined in blue). Why does rotated graphene exhibit this behavior? (Hint: It has something to do with moiré patterns.) The figure depicts what two layers of carbon atoms might look like when arranged in a hexagonal lattice. In fact, Jarillo-Herrero’s team made their discovery while trying to create graphene twists that matched a bunch of magic rotation angles from this earlier prediction, including 1.05 degrees, 0.5 degrees and 0.24 degrees. MacDonald, both then at the University of Texas, Austin. That interesting things would happen at around this magic angle had been mathematically predicted by the theorists Rafi Bistritzer and Allan H. Freedman reported in his Quanta article “ With a Simple Twist, a ‘Magic’ Material Is Now the Big Thing in Physics.” Freedman highlights a stunning discovery made by the experimental physicist Pablo Jarillo-Herrero and his colleagues at the Massachusetts Institute of Technology: When a layer of graphene, a sheet of carbon crystal with atoms arranged in a hexagonal one-atom-thick lattice, is dropped on another one and rotated to just the correct angle of about 1.1 degrees, the graphene magically acquires the ability to become superconductive when the requisite number of electrons are added.

Recently, moiré effects have also entered the quantum realm in a big way, as David H. Today, moiré patterns are seen not only in visual fields such as optics, art, photography and color printing, but also in seemingly far-flung areas like marine engineering and the detection of forged banknotes. The name moiré (pronounced mwa-ray) is etymologically related to the French word for mohair and entered the language centuries ago, describing rippled or watered fabrics. Whether you’re into art or science, engineering or fashion, you have probably seen or at least heard of these moiré patterns. When two very similar grids with light and dark elements overlap, new sinuous patterns emerge that seem to shimmer and flow.

Physics artwork