Last week, two papers by South Korean scientists made an extraordinary claim that sparked a social media frenzy and pushed up prices of some stocks in China and South Korea: the discovery of a practical superconductor.
Superconductors are materials that allow electrical current to flow with no resistance, a property that would revolutionise power grids where energy is lost in transmission as well as advance fields such as computing chips, where electrical resistance acts as a speed limit.
The papers, which appeared on a website used by scientists to share research before formal peer review and publication, spurred researchers around the world — including in at least two US national labs and three Chinese universities — to take a closer look at the proposed material.
Superconducting materials already exist in places like MRI machines for medical imaging and some quantum computers, but only display their superconducting properties at extremely low temperatures, making them impractical for wide use.
The South Korean researchers last week said they found a superconductor that works at room temperature.
The researchers also published a recipe for making the material — dubbed LK-99 — which involves taking a relatively common mineral called lead apatite and introducing a small number of copper atoms into it.
The South Korean researchers published two papers — one initial paper with three authors and a second, more detailed paper with six authors that included only two of the authors from the first paper.
Physicists said the good news is that there is no law of physics that says a room temperature superconductor cannot exist, and the material described by the South Korean team is easy to grow, meaning other researchers should be able to start getting results as soon as this week.
The gold standard for proof of discovery is other labs reliably replicating the South Korean researchers’ findings.
Researchers from at least three Chinese universities have in recent days said they produced versions of LK-99 with varying results. One team from the Huazhong University of Science and Technology posted a video purporting to show the material levitating over a magnet, which is important because true superconductors can float over a magnet in any orientation, without spinning like a compass.
But another team, from Qufu Normal University, said they did not observe zero resistance, one of required characteristics of a superconductor. A third, from the Southeast University in the eastern Chinese city of Nanjing, said they measured zero resistance, but only at a temperature of 110 Kelvin (-163C).
The possible bad news for LK-99 is that the superconducting field is full of materials that hold promise at first but fall apart under scrutiny. Researchers even have a handy name for them — unidentified superconducting objects.
“We call them USOs,” said Mike Norman, a condensed matter physicist at Argonne National Laboratory. “There’s a long history of USOs going a long way back, including some very famous people who thought they had a superconductor and they didn’t. It’s like anything in science — you can be fooled. Even good people can be fooled.” Norman said the original papers had problems. Some may have been honest typographical mistakes from rushing to post the research, but more troubling was a lack of data over a broad temperature range to show how the material behaves when it is in a superconducting state and when it is not.
“People often use that method to show how much of the sample is actually a superconductor and how much of it is not,” Norman said. – Reuters