Even if LK-99 isn’t a room-temperature superconductor, “we’ll still learn something”

A Korean research team has made international headlines by claiming they have achieved world-first superconductivity at room temperature and ambient pressure.

Considered one of the holy grails of materials science, room-temperature superconductors could have a transformative impact by making power grids more efficient, helping develop renewable technologies, revolutionising electronics, providing a new platform for quantum computing, or even in engineering super-fast transportation.

Problems of extremes

Superconductors are special because they have little to no electrical resistance and they expel magnetic fields. Zero electrical resistance means superconductors have potential to transmit power without any loss. One remarkable effect of magnetic field expulsion in superconductors is that they levitate in the presence of a magnetic field.

But superconductivity has thus far only been seen under extreme conditions. Temperatures hundreds of degrees below zero and crushing pressures are required for superconductivity to be observed in a select few materials.

“High temperature” superconductors are those that exhibit superconductivity at temperatures higher than the boiling point of nitrogen (−196.2°C; 77 degrees above absolute zero).

The highest reliable temperature at which superconductivity has been observed is −135°C, seen in a class of compounds known as cuprates.

In 2020, US physicists believed they had developed a material that conducted electricity with zero resistance at 15°C, and at crushing pressures. But that claim later had to be retracted as further research raised doubts over its validity.

Scientists are always looking to engineer new materials that exhibit superconductivity at higher temperatures and lower pressures – thereby bypassing the inconvenient and costly apparatuses that prevent its widescale practical use.

Lukewarm response to new room-temperature claims

The room-temperature superconductor is described in two papers which are yet to be peer reviewed, but are available on the preprint website arXiv.

Using a modified lead-apatite structure, referred to as LK-99, the authors claim the compound (Pb_10−xCu_x(PO₄)₆O) exhibits zero electrical resistance “and the levitation phenomenon [known as the] Meissner effect of a superconductor at room temperature and atmospheric pressure”.

Some scientists have raised doubts and suggested “fishy” and “sloppy” data supporting the bold claim.

According to Asia Financial, at least two of the co-authors have said the papers were published online without the consent of the researchers.

Dr Richard Taylor, principal research fellow in the Queensland University of Technology Faculty of Engineering, tells Cosmos that issues in scientific methods are not uncommon. He also notes that disagreements about when results are announced is “the undesirable normal behaviour of people in a hurry.”

 “If you’re on a team of experimental and theoretical physicists, you don’t get much out in the Sun,” Taylor comments.

“If you’ve got a chance of getting published first, it’s a big deal. I’m not trying to be derogatory, but it does put pressure on everybody to publish on the off chance that you’re right.

“The downside is if people say, ‘nice, but no cigar, it’s actually a semiconductor, it’s looking like a diamagnetic,’ you then have to come out and say, ‘oops, we made a mistake.’”

Is room-temperature superconductivity possible?

A Chinese experimental team released a video on social media which claims to reproduce the result of the Korean researchers, showing a tiny sample of LK-99 levitating.

“The Chinese group have said that LK-99 has some characteristics of superconductivity, but its material response to current flow looks more like a semiconductor rather than a superconductor,” says Taylor, “and what looks like a Meissner effect could be a diamagnetic response.”

“Theoretical physicists have hypothesised that there is really no high-end temperature limit on the appearance of superconductivity materials,” Taylor notes.

“We’ve all seen, not so much hoaxes, but just people getting a little bit enthusiastic about trying to define what superconductors are.”

Hot or not, the research may be valuable

Taylor remains optimistic that, whether or not the Korean researchers have achieved room-temperature superconductivity, it is worth keeping the conversation going.

“I think these announcements are really exciting. They are important to report, they’re important to keep in front of everybody. When I talk to industry about the potential of superconductivity, they ask ‘Well, can I have a bit?’ Well, maybe not today. But there’s potential.”

Taylor recommends allowing scientists around the world to test the claims before jumping to conclusions about their validity.

“Even if it’s a bit dodgy, we’ll still learn something,” Taylor notes. “That’s the point. We always learn something because we don’t fully understand superconductivity. When a new thing like this comes along, it helps a little.”