Aleksandr Rodin

A sheet of graphene one atom thick is like a flexible metal mesh through which electrons zip almost unimpeded. Stack two such sheets with a slight twist, and the material's properties change dramatically: it can become an insulator that blocks current.

A wafer-thin film of organic molecules was grown on a silicon substrate. In this film, as if on a sheet of graph paper, tiny "pens"—artificial atoms — were laid out with the tip of a scanning tunneling microscope.