Researchers have long been fascinated with two-dimensional systems, in which electrons often obey different rules from those that apply in the bulk. For decades, scientists have exploited the surprising and useful phenomena exhibited by electrons that form an effectively 2D gas at the interfaces between layered semiconductors.
Graphene, a single plane of carbon atoms in a hexagonal lattice, comes closer to the 2D ideal than do the semiconductor electron gases. Moreover, graphene has unique electronic properties that researchers are eager to measure. That’s why those in the field were so excited in 2004 by the demonstration of a technique to isolate and study what is essentially the top sheet of the layered carbon compound, graphite. (See the article by Andrey Geim and Allan MacDonald in Physics Today, August 2007, page 35.)
Alas, comments Geim, “While other areas of graphene research have emerged and developed, quantum transport measurements have...
