Scientists have discovered a fundamental process required for Superconductivity This could happen at higher temperatures than previously thought. It could be a small but important step in the search for one of physics’ holy grails: a superconductor that works at room temperature.
The discovery, made inside an unexpected material called a dielectric, reveals that electrons pair at temperatures as low as minus 190 degrees Fahrenheit (minus 123 degrees Celsius) — one of the secret ingredients for electricity to flow with almost no energy loss in extremely cold superconducting materials.
So far, physicists are still puzzling over why this happens. But understanding it could help them find superconductors that work at room temperature. The researchers published their results on August 15 in the journal sciences.
“The electron pairs tell us that they are ready to become superconductors, but something is holding them back,” says co-author Ki John Choa graduate student in applied physics at Stanford University, He said in a statement:“If we can find a new way to synchronize the pairs, we might be able to apply that to building higher-temperature superconductors.”
Superconductivity arises from the ripples that electrons leave as they move through a material. At low enough temperatures, these ripples attract atomic nuclei to each other, which in turn causes a slight shift in charge that attracts a second electron to the first.
Normally, the two negative charges should repel each other. But instead, something strange happens: the electrons bond together to form a “copper pair.”
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Cooper couples follow different paths. quantum mechanics These Cooper pairs are different from those of single electrons. Instead of being packed into energy shells, they behave like particles of light, an infinite number of which can occupy the same point in space at the same time. If enough of these Cooper pairs are created throughout a material, it becomes a superfluid, flowing without any loss of energy due to electrical resistance.
The first superconductors, discovered by Dutch physicist Heike Kamerlingh Onnes in 1911, transitioned to a state of zero electrical resistance at unimaginably cold temperatures—near absolute zero (minus 459.67 degrees Fahrenheit, or minus 273.15 degrees Celsius.) However, in 1986, physicists discovered a copper-based material, called cuprite, that becomes a superconductor at a much higher (but still very cold) temperature of minus 211 degrees Fahrenheit (minus 135 degrees Celsius).
Physicists had hoped that this discovery would lead to room-temperature superconductors. However, insights into what makes cuprates exhibit their unusual behavior have been slow to emerge, and last year viral claims of viable room-temperature superconductors ended up Data fraud allegations and disappointment.
To investigate further, the scientists behind the new research turned to a material called neodymium cerium copper oxide. This material has a superconducting temperature of minus 414.67 degrees Fahrenheit (minus 248 degrees Celsius), so scientists didn’t bother studying it too much. But when the researchers involved in the study shined ultraviolet light on its surface, they noticed something strange.
Normally, when light beams, or photons, hit Coopers carrying unpaired electrons, the photons give the electrons enough energy to knock them out of the material, causing them to lose a lot of energy. But the electrons in Cooper pairs can resist their photon ejection, causing the material to lose only a tiny amount of energy.
Although the zero-resistance state only occurs at extremely low temperatures, the researchers found that the energy gap persisted in the new material up to 150 K, and that the coupling was, oddly, strongest in most of the samples that were best at resisting the flow of electrical current.
This means that although cuprite is unlikely to achieve room-temperature superconductivity, it may hold some clues to finding a material that can.
“Our results open up a potentially rich new path forward. We plan to study this pairing gap in the future to help engineer superconductors using new approaches,” lead author Qi-Shun Shen, a professor of physics at Stanford, said in the statement. “On the one hand, we plan to use similar experimental approaches to gain more insight into this incoherent pairing state. On the other hand, we want to find ways to manipulate these materials to force these incoherent pairs into synchrony.”
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