In Shenzhen, physicist Zhuoyu Chen told a machine to lay down three layers of atoms. Then he measured the resistance and saw a number no one had ever read without a diamond press: 45 kelvin.
Three layers of atoms in a chamber
Zhuoyu Chen watches the screen. In the vacuum chamber of his laboratory at the Southern University of Science and Technology in Shenzhen, a laser alternately vaporises two targets — lanthanum oxide and nickel oxide. Atom by atom, layer by layer, like a bricklayer laying bricks, except each brick is the size of a single atom.
This isn't Chen's first time. The machine his team named GOALL-Epitaxy can lay down oxides with better than one-percent precision. But this time the stakes are different. The film growing under the laser is exactly three unit cells thick — under seven nanometres, less than the diameter of an influenza virus.
As they cool the film, the electrical resistance begins to fall. At 45 kelvin — minus 228 degrees Celsius — the curve breaks downward. Chen sees what no one had seen before without a diamond press: superconductivity above the 40-kelvin mark, at ordinary atmospheric pressure.
And now the thing that shouldn't add up. To reach the same state in a bulk crystal, it had to be squeezed with 14 gigapascals of force — that is, 140,000 atmospheres. It's like placing the weight of over a hundred cars on a single square centimetre. And Chen achieved the same thing by compressing a layer of atoms by just two percent.
He didn't crush the crystal. He stretched it onto a substrate.
140,000 atmospheres in a vice
The story begins a decade earlier, on the other side of the Pacific. In 2019, Harold Hwang of Stanford University discovered that infinitely thin layers of neodymium nickelate — a cousin of the famous cuprates, the high-temperature superconductors — could also superconduct. It was barely 15 kelvin, but it was enough to send the world of physics into a frenzy.
Because nickelates are a new family of materials with a structure almost identical to the cuprates, but different orbital chemistry — and every condensed-matter physicist knows that a second way to the same problem is often the path to understanding it.
The real shock came in 2023. Sun Hualei's team from the Institute of Physics of the Chinese Academy of Sciences announced in Nature that the bilayer nickelate La₃Ni₂O₇ superconducts at 80 kelvin. Eighty. That's above the boiling point of liquid nitrogen — 77 kelvin — the threshold above which cooling stops being expensive.
There was just one catch. To get the nickelate to those 80 kelvin, it had to be forced into a diamond anvil and squeezed to 14 gigapascals. That's the pressure found in nature about 400 kilometres beneath the Earth's surface.
Chen followed these reports closely. The problem was simple to state and fiendishly hard to solve: a superconductor that works only in a diamond press is useless. You can't build a cable or a magnet from it.
The film that refused to superconduct
Chen and his four first authors — Guangdi Zhou, Wei Lv, Heng Wang and Zihao Nie — spent months on attempts. Their first goal seemed simple: grow a clean La₃Ni₂O₇ film and check whether it superconducts at normal pressure.
It didn't.
In measurements the team later described in the supplementary materials, the clean film showed only 'a slight drop in resistance around 10 kelvin, without reaching zero resistance'. In plain terms: the material almost superconducted, but not quite. The resistance fell, but did not vanish. That's the worst possible result — too close to success to give up, too far to build anything from it.
Then the oxygen problem hit them. The nickelate films turned out to be so oxygen-hungry that above 200 kelvin, under even slightly imperfect vacuum, they lost oxygen atoms and the superconductivity died. The team had to keep the samples cold and develop a whole ritual of ozone annealing — thirty minutes at 575 degrees Celsius under 15 pascals of ozone — just to keep the oxygen where it belonged.
Chen also tested different cooling rates: 50 degrees a minute, 60 degrees a minute. No difference. Blind alleys that never make it into a paper's title. They eat weeks.
This was a failure that couldn't be outsmarted. The entire field had been stuck in it for two years: everyone knew that bilayer nickelates superconduct under pressure, but no one — not in the States, not in China, not in Europe — could achieve the same at room pressure.
Instead of squeezing — stretching
The breakthrough wasn't a better crystal. It was a different question.
Why squeeze a material from the outside when you can stretch it from within? Chen realised that pressure does only one thing: it compresses the crystal lattice and forces the atoms into the tetragonal phase that superconducts. And if so, the same effect could be produced another way — by laying a thin film on a substrate with a slightly smaller lattice constant.
The SrLaAlO₄ substrate has a lattice constant of 3.75 ångströms. Free nickelate has 3.832 ångströms. The difference? About two percent. When Chen had the machine grow a three-unit-cell nickelate film on this substrate, the film's lattice had to match the substrate and compressed by those two percent — exactly as if a press had squeezed it, only without the press.
The doped element also proved key. Pure La₃Ni₂O₇ wouldn't cooperate — so the team replaced some of the lanthanum with praseodymium, obtaining La₂.₈₅Pr₀.₁₅Ni₂O₇. Praseodymium, with its smaller ionic radius, improved the purity of the bilayer structure and eased the diffusion of strontium from the substrate.
The result? The onset of the superconducting transition at 45 kelvin. Zero resistance at lower temperature. The Meissner effect — the expulsion of a magnetic field, the signature of true superconductivity — confirmed by an independent measurement.
It's still not 77 kelvin. But Chen opened a door the entire field has been knocking on for a decade: nickelates can now be studied and — perhaps — used without a diamond anvil.
The race no one is watching
Chen didn't run alone. When his preprint hit arXiv in December 2024, on the other side of the Pacific Harold Hwang — the same physicist who discovered the first superconducting nickelate in 2019 — was working on an identical idea. A month later, the Stanford and SLAC group published its own result: superconductivity in strained La₂PrNi₂O₇ films, also at room pressure.
Two laboratories. Two continents. One solution — strain engineering.
More teams joined the race. In Nanjing, strontium doping yielded superconductivity in thin nickelate films. In Tokyo, Motoki Osada's team at RIKEN showed that by changing the substrate one can tune the transition temperature across a range of as much as 50 kelvin — from 10 to 60 kelvin — merely by choosing what the film grows on.
Chen leads this race. His 45 kelvin is the highest transition temperature achieved in nickelates at atmospheric pressure. But the lead is fragile: everyone is chasing the same 77-kelvin threshold.
What good is a superconductor at 45 kelvin
Superconductors are the silent foundation of modern technology. Every MRI scanner, every magnet in a particle collider, every qubit in a quantum computer rests on a material that, at low temperature, conducts current with zero resistance.
The superconductor market is estimated at roughly 8–9 billion dollars a year, with MRI magnets as its largest part. But what really drives the race are three goals.
The first is nuclear fusion. The SPARC reactor of the American company Commonwealth Fusion Systems is to contain superconducting magnets made of REBCO tape capable of producing a 20-tesla field. Each such reactor means hundreds of kilometres of superconducting wire.
The second is quantum computers. Superconducting qubits — the ones in Google's and IBM's machines — require materials with perfectly controlled properties. Thin films are exactly the form in which they are made.
The third is lossless power transmission. Superconducting cables can carry many times more current than copper ones of the same cross-section, but today's high-temperature superconductors are brittle ceramics from which it is extremely hard to make flexible wire.
Nickelates are different. They grow as thin films — and thin films are exactly the form in which electronics are made. The threshold the whole field is fighting for is 77 kelvin. Above it, cooling becomes cheap — liquid nitrogen costs pennies a litre, instead of liquid helium, whose price can reach tens of dollars a litre.
Chen showed that nickelates are a step away from that threshold. And that the path to it is strain engineering, not a press.
Wrocław has low temperatures
Poland doesn't grow superconducting nickelates. But it has exactly the building blocks such work is made of.
In Wrocław there is the Institute of Low Temperature and Structure Research of the Polish Academy of Sciences — an institution that has studied superconductivity and magnetism at extremely low temperatures for decades. At the Warsaw University of Technology, Piotr Guńka publishes on clathrate superconductors — materials in which a metal enclosed in a boron cage superconducts under pressure. At AGH in Kraków, the team of Maciej Wielgosz and Andrzej Skoczeń co-authored an international roadmap for how artificial intelligence should accelerate the search for new superconductors.
There's also the practical side. At the Wrocław University of Science and Technology, the group of Przemysław Borowski and Jarosław Myśliwiec develops magnetron sputtering — the same family of thin-film deposition techniques that Chen perfected in Shenzhen.
And the demand is real and growing. Poland participates in the European fusion programme through the Institute of Plasma Physics and Laser Microfusion — and every fusion reactor, from ITER to America's SPARC, needs superconducting magnets. The Poznań Supercomputing and Networking Center is building competence in quantum computing, where superconducting qubits are the standard.
What's missing is one link: a team that would connect Polish thin-film deposition with superconducting nickelates. This isn't a job for a single PhD student. It's a project on the scale of a national laboratory — and exactly the kind of moment Chen showed pays off.
Sources
Zhou G., Lv W., Wang H., Nie Z., Chen Y., Li Y., Huang H., Chen W., Sun Y., Xue Q.-K., Chen Z., Ambient-pressure superconductivity onset above 40 K in bilayer nickelate ultrathin films, Nature (2025). DOI: 10.1038/s41586-025-08755-z
Sun H. et al., Signatures of superconductivity near 80 K in a nickelate under high pressure, Nature 621, 493–498 (2023). DOI: 10.1038/s41586-023-06408-7
Li D. et al., Superconductivity in an infinite-layer nickelate, Nature 572, 624–627 (2019). DOI: 10.1038/s41586-019-1496-5
Wang N. et al., Bulk high-temperature superconductivity in pressurized tetragonal La₂PrNi₂O₇, Nature 634, 579–584 (2024). DOI: 10.1038/s41586-024-07996-8
Liu Y. et al., Superconductivity and normal-state transport in compressively strained La₂PrNi₂O₇ thin films, Nature Materials 24, 1221–1227 (2025). DOI: 10.1038/s41563-025-02258-y
Zhou G. et al., Gigantic-oxidative atomic-layer-by-layer epitaxy for artificially designed complex oxides, National Science Review (2024). DOI: 10.1093/nsr/nwae429
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