The honeycomb lattice is one of nature’s favorite patterns. In the two-dimensional crystal of carbon atoms known as graph­ene, for instance, the honeycomb structure arises from bonds among the atoms. Kenjiro K. Gomes of Stanford University and his colleagues have learned to make a honeycomb material in a striking new way. They place carbon monoxide molecules at regular intervals on the surface of a copper crystal, creating an imitation graphene layer. (The added molecules appear as black dots.)

By tweaking the pattern, the researchers can investigate how variations of small-scale structure change a material’s electric properties. In the image at the left, a slightly deformed honeycomb lattice forces the electrons to behave as if they were subjected to intense magnetic fields. Such “designer materials” may lead to the discovery of new and exotic physics.