Scientists at the University of Southern California may have discovered a family of materials that could make superconductors that work at room temperature.
Superconductivity is where electricity is transmitted without any resistance, meaning that no energy is lost. Superconductors are already used in specialty equipment such as MRI machines, and maglev trains, but if they could be made to work at room temperature all electronic devices could be made to be super-efficient.
The scientists, led by Vitaly Kresin, professor of physics at USC, found that aluminum “superatoms” – homogenous clusters of atoms – appear to form Cooper pairs of electrons (one of the key elements of superconductivity) at temperatures around 100 Kelvin.
Although that is still a long way from room temperature (100 Kelvin is about -173 degrees Celsius) it’s a big improvement on bulk aluminum metal, which turns superconductive only near 1 Kelvin (-272 degrees Celsius).
“This may be the discovery of a new family of superconductors, and raises the possibility that other types of superatoms will be capable of superconductivity at even warmer temperatures,” said Kresin.
Cooper pairs were first predicted in 1956 by Leon Cooper. They consist of two electrons that attract one another in some materials under certain conditions, such as extreme low temperatures. Kresin explains
Imagine you have a ballroom full of paired-up dancers, only the partners are scattered randomly throughout the room. Your partner might be over by the punch bowl, while you’re in the center of the dance floor. But your motions are done in tandem – you are in step with one another. Now imagine everyone changes dance partners every few moments. This is a commonly used analogy for how Cooper pairing works.
USC discusses the significance of Cooper pairs in its public release announcing the discovery:
When electrons flow through a material, they bump into various imperfections that knock them off course. That’s the resistance that causes energy loss in the form of heat.
If the electrons are mated up into Cooper pairs, however, that connection is just strong enough to keep them on course regardless of what they bump into. Cooper pairs are what make superconductivity work.
Superatoms are clusters of atoms that in some ways behave as if they were a single atom – the free electrons become defined by the cluster rather than single atoms but flow as if in a single atom’s electron cloud. The USC scientists’ research suggests that they may also exhibit Cooper pairing as if they were single atoms.
The next step will be to explore the superconductivity of various sizes of superatoms and various elements to make them.
Kresin envisions a future in which electronic circuits could be built by placing superatoms in a chain along a substrate material, allowing electricity to flow unhindered along the chain.
“One-hundred Kelvin might not be the upper-temperature barrier,” Kresin said. “It might just be the beginning.”
Bill Condie is a science journalist based in Adelaide, Australia.
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