When researchers claimed recently that they had created a material that perfectly conducts electricity 鈥� a superconductor 鈥� and that it does so at room temperature and pressure, many people were understandably sceptical. Such a finding would be transformative to many areas of science and technology. Now, labs around the world have kicked into action in a race to create and test the new material, called LK-99, to see if it really is what its creators claim.
Superconductors could radically increase the efficiency of many technologies, including magnetic levitation and nuclear fusion, but at the moment they are highly impractical because they need ultra-low temperatures or ultra-high pressures to function.
If LK-99 is a room-temperature and pressure superconductor, that would change the situation dramatically. However, the evidence for this presented by at the College of William & Mary in Virginia and his colleagues has left many researchers unconvinced.
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Two independent research teams say they have now recreated LK-99 in their own labs. They have both tested whether it is a superconductor at room temperature and pressure 鈥� and both say they have found no evidence that it is.
鈥淎s of today, our answer is [that it is] not superconducting,鈥� says at the National Physical Laboratory of India, who led one of the teams.
for creating LK-99 outlined in two papers that first introduced the material. They then used X-rays to confirm that the structure of what they had made was consistent with the original descriptions.
To test the superconductivity of their LK-99, the researchers measured its electrical resistance and how it reacted to magnetic fields, again mirroring the work of Kim鈥檚 team. The results of both tests did not indicate superconductivity.
The , carried out by at Beihang University in China and his colleagues, followed a similar procedure and also did not uncover any signs of room-temperature and pressure superconductivity. They also tested whether their sample levitated over a large magnet 鈥� something that happens with superconductors 鈥� but had no success.
In Kim鈥檚 view, in both cases the issue lies in how well the researchers were able to manufacture LK-99. 鈥淲e gave some comments to the group in India. I think they are having challenges with making high-quality samples,鈥� he says.
Other research groups, including at , appear to be working on similar replications. Early reports of a levitating sample of LK-99 at the Huazhong University of Science and Technology in China have also been . Such levitation would not, by itself, rule out magnetic phenomena distinct from superconductivity.
Alongside these experiments, researchers have been working on better understanding what the electrons inside LK-99 could be doing to give it special properties. at the Lawrence Berkeley National Laboratory in California used computer simulations to of electrons in LK-99 based on the arrangement of the compound鈥檚 atoms.
Her computations revealed that some electrons may have properties like those in some other, more established superconductors. However, these properties could also be caused by other phenomena like exotic magnetism, says Griffin. 鈥淪uperconductivity is an option, but it is not a guaranteed,鈥� she says.
Teams led by聽聽at the University of Colorado Boulder and聽聽at the Chinese Academy of Sciences, as well as at the Vienna Institute of Technology in Austria and at Northwest University in China, have also independently carried out 听补苍诲听聽as Griffin, thus bolstering the claim that even if LK-99 is not a miracle superconductor, it is at least unusual for its class of materials.
at the Humboldt University of Berlin in Germany says these calculations imply that LK-99, as simulated, has some surprising and promising electronic properties. Calculations that would prove superconductivity more definitively are still missing, but Griffin鈥檚 work is a first and necessary step towards discerning what exotic phenomena, like superconductivity but also certain types of magnetism, could be at play here, he says.
However, some of the assumptions that went into the calculations may not fully represent the material tested by Kim鈥檚 team, says at Princeton University. That is because the original analysis of how LK-99鈥檚 atoms were arranged was 鈥渘ot up to community standards鈥�, she says. Other chemists the way Kim鈥檚 team analysed X-ray data to establish this arrangement as imprecise.
The saga of this potential superconductor will continue as more teams announce the results of their attempts to create and test it.
Griffin says that one sticking point from her computations is that copper atoms inside of LK-99 must be in just the right place to support the special electronic properties that her computations revealed, yet that configuration is not necessarily the most likely outcome when making the material. 鈥淚 have lots of colleagues that are trying to make this thing and that鈥檚 a useful piece of information for them,鈥� she says.
For Awana and his team, improving the quality of their samples is crucial. 鈥淢ore trials are underway to get better-quality LK-99 and to reproduce its reported superconductivity. Having been a player in the field of superconducting materials for over 35 years, I believe this is possible and that LK-99 is to date the most promising case for room-temperature ambient-pressure superconductivity,鈥� he says.
