Superconductivity holds great promise for delivering energy without the usual losses due to heat and electrical resistance that we find with regular power lines, but it is notoriously tricky to achieve. A new type of superconductor may help us better understand how they work 鈥� and bring us one step closer to using them in everyday life.
Superconductors transfer energy without any resistance, but they generally only work at extremely low temperatures. This makes them difficult to create and even harder to put to any practical use. Among the warmest operators are cuprate superconductors, which work at -173掳C. But these are messy electrical systems that are difficult to understand and recreate.
at the Massachusetts Institute of Technology and his colleagues have made a superconductor that exhibits the same kind of resistance-free energy transfer as cuprates but is much less complicated. It is also easy to switch between superconducting and insulating states, which makes it easier to study how superconductivity comes about.
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The material is made from two layers of graphene 鈥� a form of carbon that is pliable yet incredibly strong, and a superb conductor of heat. Each layer is less than 30 nanometres thick and features a hexagonal pattern of molecules.
The two layers are stacked, with one rotated by about 1 degree with respect to the other, creating a pattern of overlapping hexagons. This changes the way the electrons within the lattice interact with one another such that they can flow through without resistance when a voltage applied to the system is increased.
Twisting a dial
This transformation from an insulator to a superconductor occurs at around -271掳C, which may seem quite cold but is fairly warm compared with the temperatures at which many other superconductors operate.
鈥淭his is a striking result 鈥� a clean system that appears to show the same kind of superconductivity that we鈥檝e been trying to understand in cuprates for three decades,鈥� says at Harvard University.
鈥淭his is a dramatic change in the physical properties that can be brought about very simply by just twisting a dial, so you can study that very systematically,鈥� says at MIT, who wasn鈥檛 involved in this research. Such a systematic study isn鈥檛 possible in cuprates, which require labour-intensive changes in their chemical make-up to turn from insulators to conductors.
Studying this system could help us figure out the physical mechanisms behind superconductivity. This could show us how to induce it in other materials, which could lead to superconductors that work at higher temperatures.
Because this material is easy to turn from an insulator to a superconductor and back again, Jarillo-Herrero says that it could be used to make superconducting transistors for use in quantum computers or other sophisticated electronic applications.
Nature
Read more: The world in 2076: Goodbye electricity, hello superconductivity
