In recent years, engineers have found ways to modify the properties of some “two- dimensional” materials, which are just one or a few atoms thick, by stacking two layers together and rotating one slightly in relation to the other. This creates what are known as moiré patterns, where tiny shifts in the alignment of atoms between the two sheets create larger-scale patterns. It also changes the way electrons move through the material, in potentially useful ways. But for practical applications, such two-dimensional materials must at some point connect with the…