Wish your smartphone could keep its cool? Then discard its wasteful silicon chip and get on the stanene superhighway instead
Slick though our smartphones might seem on the outside, inside there’s a lot of bumbling going on. The electrons that transport information through their processor chips make less than stately progress. “In a solid, electrons move like in a crowded marketplace, bumping into things like impurities,” says , a physicist at Stanford University in California.
If your phone seems to be burning a hole in your hand, or is dead again just hours after charging, this electronic ineptitude is mainly to blame. Every electron collision generates heat. In the cramped confines of an integrated circuit, waste heat becomes an almost insurmountable problem. The impossibility of transporting it away quickly enough is the principal factor slowing the development of chips that can do more with less.
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A material that conducts electricity without producing all that bothersome heat would be a huge boon. For over a century, physicists have tantalised engineers with just the thing: superconductors. But most superconductors work only at temperatures close to absolute zero. Despite sustained efforts, we are still only halfway to a superconductor that works at room temperature.
Zhang’s riposte lies with a new class of materials known as topological insulators. They were first made in 2007. As their name suggests, they are mainly electrical insulators – except at their surfaces, where electrons are free to move. As these electrons pass by surface atoms, a quantum interaction known as spin-orbit coupling kicks in that prevents them either from making U-turns or from burrowing into the body of the material. They end up forced to whizz up one side of the material, and back down the other. Compared with the electron movement in today’s gadgets, says Zhang “these electrons move like they are on a superhighway or autobahn”.
Although probably not a very safe one. In topological insulators to date, electrons might still slalom across “lanes” within the surface layer and dissipate heat – unless, again, they were cooled to within a whisker of absolute zero.
Stanene could keep them on the straight and narrow. Like its more famous wonder-cousin graphene, it is a “two-dimensional” sheet of a single element – in this case, tin – just one atom thick. The thinness of the sheet puts an extra restriction on the electrons’ movement that leaves them no option but to zoom up and down the materials’ edges, even at room temperature (). It could be just the material for zero-heat-loss interconnects in processor chips, and it might make a nifty thermoelectric material too (see “Wonder stuff: Heat scavengers promise energy bonanza“).
In theory, at least. At the moment, stanene exists only on paper, although rumours abound that its synthesis will soon be announced. If it works as predicted, Zhang thinks all the pieces are in place for topological insulators to race into the big time, and into our devices. “If I’m optimistic I’ll say five years,” he says. “If I’m realistic, 10”.
Question is, can we wait that long for a phone that stays charged for months?
Read more: “Wonder stuff: Seven new materials to change the world“
This article appeared in print under the headline “Future stuff: Stanene”
Article amended on 1 January 1970
When this article was first published, it mentioned “topical” insulators instead of topological insulators in one place.
