As electronics continue to shrink, they're constantly pushing up against the limits of our ability to craft increasingly tiny features. Processors rely on features etched with extremely high-energy light, and disk drives store information in ever-smaller clusters of atoms. As these features shrink, electrical, magnetic, and even quantum interference begin to dominate, and it becomes ever more difficult to maintain and detect signals such as the state of a memory bit. To avoid these issues entirely, scientists have started to explore the possibility of storing information in the chemical structure of single molecules. A team of European researchers reported a new approach to single-molecule storage that may bring these devices closer to stepping out of the lab.
Molecular memory will require chemicals that can switch back and forth between two stable states, much the way clusters of atoms switch magnetic states on the surface of disk drives. It's relatively easy to find molecules that can behave the same way. So far, however, most of these molecular switches involve structural changes: large parts of the molecule move relative to each other when changing states. This can work well in lab settings, but it isn't ideal in the real world, where it may not be compatible with a stable and reliable material that's easy to manufacture. The approach described in the new research relies on a molecule that's physically flat and changes states by shifting the location of hydrogen atoms without undergoing any structural changes. Even better, the memory states can be changed and read through the same technique used in electronics today: changes in electrical conduction.