Superconductivity occurs when electrons in a metal move in pairs and move through a material without resistance. But there may be more to the story than we thought, as scientists in Germany have now discovered that electrons can also be combined into families of four to create a new state of matter, and possibly a new kind of superconductivity.
Conductivity is a measure of how easily electrons can move through a material. But even in materials that are good conductors like gold, electrons still encounter some resistance. But superconductors can remove all these barriers and provide zero resistance at ultra-low temperatures.
Electrons move so easily in superconductors because they pair through a quantum effect known as Cooper pairing. In this case, they raise the minimum energy needed to interfere with electrons — if the material is cold enough, its atoms don’t have enough thermal energy to interfere with these Cooper pairs, allowing electrons to flow freely without losing energy.
But in the new study, researchers from the Universities of Dresden and Würzburg in Germany have made a fascinating discovery. They found in a special type of superconductor that Cooper pairs themselves are pairing up and forming families of four electrons.
“When we found that suddenly there were four electrons instead of two forming a bond, we first thought it was a measurement error,” said Henning Klauss, lead researcher on the study, “but the more methods we used to confirm that This result, the more it becomes clear that this must be a new phenomenon: All the data agree with the same result. Now we know that a family of four-particle electrons in certain metals creates a whole new kind of matter when cooled to ultra-low temperatures state.”
The discovery was made in a superconducting metal containing barium, potassium, iron and arsenic, which belongs to a class known as iron-phosphorus compounds. This phenomenon has been theoretically predicted about a decade ago, but no experimental evidence has emerged until now. The researchers then spent two years confirming the finding using seven different methods.
These electron families could open up a new branch of superconductivity and a range of advanced devices that exploit it, the team said. But until then, there is still a lot of work to be done to unravel how it works, in which materials it happens and how it can be invoked.
“One can hypothesize that our results will lead to a whole new direction of research, such as finding other metals with four connected electrons or exploring how materials need to be altered to create a family of electrons. From a purely theoretical point of view, using our electrons A completely new kind of superconductivity can also be achieved with the group. The only certainty is that, due to their new aggregated state, iron phosphorus group elements are well suited for technologies such as quantum sensors,” says Klauss.
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