Score another point for the physicists who have been working to make our electronic devices continually smaller and faster. The wires inside such devices are now so thin that electrons sometimes have trouble passing through them: A microscopic bump can seem like Mount Everest in a copper strand one-thousandth the thickness of a human hair.
But last year a group of researchers at Princeton University revealed materials whose surfaces allow electrons to move unimpeded past pesky obstacles. These intriguing materials, called topological insulators, do not allow electrons to pass through (hence the “insulator” part of their name), but their surfaces have proved to be outstanding at shuttling electrons along.
In a study whose results were published in Nature last July, physicist Ali Yazdani used a powerful microscope to track electrons as they encountered stairlike barriers on the surface of antimony, a material that shares several characteristics with topological insulators such as bismuth telluride. In a typical copper wire, most electrons would bounce back from such an obstruction and the rest would get absorbed, impeding the flow. “With copper, surface imperfections slow things down and create unwanted heat,” Yazdani explains. With antimony, however, nearly half the electrons passed right across the barrier. Yazdani thinks that topological insulators might start to replace copper in next-generation electronics.