New superconducting materials have just been discovered
The original version from this story appeared in How much magazinee.
In 2024, superconductivity – the flow of electric current without resistance – was discovered in three different materials. Two examples go beyond the textbook understanding of the phenomenon. The third one completely shreds it. “It’s an extremely unusual form of superconductivity that many people would have said wasn’t possible,” he said Ashwin Vishwanatha Harvard University physicist who was not involved in the discoveries.
Superconductivity has fascinated physicists since 1911, when Dutch scientist Heike Kamerlingh Onnes first saw the disappearance of electrical resistance. How it happens remains a mystery: the phenomenon requires the pairing of electrons that carry electric current. Electrons repel each other. So how can they be united?
Then there is the technological promise: superconductivity has already enabled the development of MRI machines and powerful particle accelerators. If physicists could fully understand how and when the phenomenon occurs, they might be able to design a wire that superconducts electricity under everyday conditions, rather than exclusively at low temperatures, as is currently the case. World-changing technologies – lossless power grids, magnetic levitation vehicles – could follow.
The recent spate of discoveries has both deepened the mystery of superconductivity and increased optimism. “It seems that superconductivity is everywhere in materials,” he said Matthew Yankowitza physicist at the University of Washington.
The discoveries stem from a recent revolution in materials science: All three new cases of superconductivity arise in devices composed of flat sheets of atoms. These materials exhibit unparalleled flexibility; At the push of a button, physicists can switch them between conducting, insulating and more exotic behavior – a modern form of alchemy that has accelerated the search for superconductivity.
It now seems increasingly likely that different causes could be responsible for the phenomenon. Just as birds, bees and dragonflies all fly with different wing structures, materials appear to pair electrons with each other in different ways. Even as researchers debate what exactly happens in different two-dimensional materials, they believe the growing zoo of superconductors will help them gain a more universal view of the tantalizing phenomenon.
Pairing of electrons
The case of Kamerlingh Onnes’ observations (and the superconductivity observed in other extremely cold metals) was finally resolved in 1957. John Bardeen, Leon Cooper and John Robert Schrieffer found out that at low temperatures the restless atomic lattice of a material calms down so that more sensitive effects emerge. Electrons gently pull on protons in the lattice, pulling them inward to create an excess of positive charge. This deformation, known as a phonon, can then attract a second electron and form a “Cooper pair.” Cooper pairs can all come together into a coherent quantum unit in a way that is not possible with single elections. The resulting quantum soup slides smoothly between the material’s atoms, which normally impede electrical flow.
Bardeen, Cooper and Schrieffer’s theory of phonon-based superconductivity won them the Nobel Prize in Physics in 1972. But it turns out it wasn’t the whole story. In the 1980s, physicists found that copper-filled crystals called cuprates could be superconducting at higher temperatures, with atomic movements washing out phonons. Other similar examples followed.
