World’s smallest superconductor discovered

You might think that the 32nm transistors buried inside your CPU are a wonder of the modern age, but they look like a veritable skyscraper compared to the world’s smallest superconductor.

Discovered by scientists headed by the University of Ohio, the superconductor works on a molecular scale, being formed of four pairs of molecules less than 1nm wide.

The team’s findings have just been published in a paper Nature Nanotechnology, and the researchers are hailing the discovery as a break-through for the future of nanoscale electronics.

Interconnects have previously proven to be a hurdle for nanoscale electronics, as standard metal conductors transfer heat as well as electricity, and the heat can easily cause the very thin metal to melt.

The paper’s lead author, Saw-Wai Hla, explained that “researchers have said that it’s almost impossible to make nanoscale interconnects using metallic conductors because the resistance increases as the size of wire becomes smaller. The nanowires become so hot that they can melt and destruct. That issue, Joule heating, has been a major barrier for making nanoscale devices a reality.”

However, the use of a nanoscale superconductor could eliminate this problem. As superconducting materials have an electrical resistance of zero, they can conduct plenty of electrical current without generating heat or losing any power. According to Hla, superconductors were considered to be a purely macroscopic phenomenon until recently, but the discovery that a superconductor can function at the molecular scale “opens up a novel route for studying this phenomenon.”

The team of scientists used tunneling spectroscopy to observe the behaviour of synthesised molecules of (BETS)2-GaCl4 (a type of organic salt) when placed on a silver substrate. According to the research, the best levels of superconductivity were found in chains of molecules above 50nm in length, and after that it started to deteriorate. However, the researchers say that the superconductivity phenomenon was still evident in chains that were formed of just four pairs of molecules.

The picture below shows the smallest working semiconductor, which has a width of just 0.87nm.