New room-temperature superconductor discovered by scientists

Scientists announced this week an incredible step towards the dream of a material that can easily transmit electricity under everyday conditions. Such a breakthrough could transform almost any technology that uses electrical energy, opening up new possibilities for your phone, magnetic trains and future fusion power plants. .

Normally, current encounters resistance as it moves through the conductors, almost like a form of friction, and some energy is lost as heat. A century ago, physicists discovered materials, now known as superconductors, where resistance seems to magically disappear. But these materials only lose their resistance to extremely low, extremely cold temperatures, which limits practical applications. For decades, scientists have been looking for superconductors that work at room temperature.

This week’s announcement is the latest in that effort, but it comes from a group that is facing widespread skepticism because a 2020 paper described a promising but less realistic superconducting material used to be withdraw after other scientists questioned some of the data.

The new superconductor consists of lutetium, a rare earth metal, and hydrogen with a little nitrogen mixed in. It needs to be compressed to a pressure of 14,500 pounds per square inch before it can achieve superconducting strength. That’s about 10 times the pressure created at the bottom of the ocean’s deepest trenches.

But it’s also 1/100 less than the required 2020 results, like the crushing force found several thousand miles deep in the Earth’s interior. That suggests that further studies of the material could lead to a superconductor that operates at ambient room temperature and at typical atmospheric pressure of 14.7 pounds per square inch.

Ranga P. Dias, professor of mechanical engineering and physics at the University of Rochester in New York, said: “This is the beginning of a new class of materials that will be useful for practical applications. at a meeting of the American Physical Society in Las Vegas.

A more complete account of his group’s findings is published Wednesday in the journal Naturethe same journal published, later retracted the 2020 findings.

The team at Rochester started with a small, thin foil of lutetium, a silvery-white metal among the rarest of the rarest earth elements, and pressed it between two interlocking diamonds. Then, a gas consisting of 99% hydrogen and 1% nitrogen is injected into a small chamber and compressed at high pressure. The sample is heated overnight to 150 degrees F, and after 24 hours, the pressure is released.

About a third of the time, the procedure produces the desired result: a small brilliant blue crystal. Dr Dias said: “Doping nitrogen with lutetium hydride is not easy.

In one of the University of Rochester laboratories that Dr Dias’ team uses, a graduate student Hiranya Pasan demonstrated the material’s surprising color-changing properties during a visit by a reporter member last week. As the screws tighten to increase the pressure, the blue color turns red.

Dr Dias said: “It is very pink. With even higher pressure, he says, “it turns bright red.”

Shining a laser through the crystals revealed how they vibrate and unlocked information about the structure.

In another room, other members of Dr. Dias’s team were making magnetic measurements on other crystals. As the temperature drops, squiggly lines are expected to appear in the data plotted on a computer screen, indicating a transition to a superconductor.

“This is a direct measurement that we are taking,” Dr. Dias said.

In the paper, the researchers reported that the pink crystals exhibit key properties of superconductors, such as zero electrical resistance, at temperatures up to 70 degrees Fahrenheit.

“I am cautiously optimistic,” said Timothy Strobel, a scientist at the Carnegie Institution for Science in Washington who was not involved in Dr. “The data in the paper, looks great.”

“If this is real, then it’s a really important breakthrough,” said Paul CW Chu, professor of physics at the University of Houston, who was also not involved in the study.

However, the “if” part of that sentiment revolves around Dr. Dias, who has been dogged by suspicions and criticisms, and even accusations by some scientists that he fabricated some data. their own material. The results of the 2020 Nature paper have yet to be replicated by other research groups, and critics say Dr Dias has been slow to let others check his data or perform independent analyses. about its superconductors.

Nature’s editors withdrew the previous paper last year over objections from Dr Dias and other authors.

“I’ve lost some faith in what’s coming from that group,” said James Hamlin, a professor of physics at the University of Florida.

However, the new paper passed the peer review process at the same journal.

A Nature spokesperson said: “The fact that a paper is withdrawn does not automatically disqualify an author from submitting a new manuscript. “All submitted manuscripts are independently reviewed on the basis of their quality and scientific timeliness.”

At Tuesday’s conference in Las Vegas, there were so many physicists packed into a cramped conference room that the moderator asked some to leave so they wouldn’t have to cancel the presentation. As the room thinned out, Dr. Dias was able to present his findings without interruption. When thanking the crowd, the moderator expressed regret that they had run out of time on questions.

Dr. Strobel acknowledges the ongoing controversy surrounding Dr. Dias and that previous extraordinary claims have yet to be reproduced.

“I don’t want to read too much into it, but there could be a pattern of behavior here,” Dr. Strobel said. “He really could be the best high-pressure physicist in the world, ready to win a Nobel Prize. Or is there something else going on.”

Under pressure

Superconductivity was discovered in 1911 by Heike Kamerlingh Onnes, a Dutch physicist, and his team. Superconductors not only carry electricity with zero fundamental resistance, but they also possess amazing abilities. A strange phenomenon known as the Meissner effect ensures that the magnetic field inside the material is zero. .

The first known superconductors required a temperature just a few degrees above absolute zero, or minus 459.67 degrees Fahrenheit. In the 1980s, physicists discovered so-called superconductors. high temperatures, but even these become superconductors under conditions much colder than in everyday use.

The standard theory explaining superconductivity predicts that hydrogen would be a superconductor at higher temperatures if it could be compressed strongly enough. But even the most resilient diamonds break before such great pressure is reached. Scientists began looking at hydrogen mixed with another element, surmising that chemical bonds might help compress hydrogen atoms.

In 2015, Mikhail Eremets, a physicist at the Max Planck Institute of Chemistry in Mainz, Germany, reported that hydrogen sulfide – a molecule consisting of two hydrogen atoms and one sulfur atom – became superconducting in temperatures of minus 94 degrees Fahrenheit when pressed to about 22 million pounds per square inch. That was a record high temperature for a superconductor at the time.

Dr. Eremets and other scientists later discovered that lanthanum hydride — a compound containing hydrogen and lanthanum — reaches a superconducting temperature of 10 degrees Fahrenheit at super-high pressure.

In the study described in the retracted 2020 paper, Dr Dias’ team used hydrogen, sulfur and carbon. With the three elements, the scientists say, they can tune the electronic properties of the compound to achieve higher superconducting temperatures.

However, not everyone believes that.

Dias’ main antagonist is Jorge Hirsch, a theoretical physicist at the University of California, San Diego. He focused on measurements that Dr Dias’ group had made of the response of carbon-sulfur-hydrogen compounds to an oscillating magnetic field, evidence of the Meissner effect. The plot in the paper seemed too neat and the scientists didn’t explain how they got rid of the background effects in the plot.

When Dr. Dias published the underlying raw data, Dr. Hirsch said, his analysis indicated that it was generated by a mathematical formula and could not be measured realistically in an experiment. “From a measurement, you don’t get analytical formulas,” says Dr. Hirsch. “You get numbers with noise.”

His complaints about Dr Dias became so persistent and acute that others in the field sent a letter complaining about Dr. Hirsch’s decades of disruptive behavior.

Dr. Hirsch is a bully at the Chinese store, targeting the BCS theory, which was devised in 2009 by three physicists — John Bardeen, Leon N. Cooper and J. Robert Schrieffer. 1957 — to explain how superconductivity works. The BCS is in many ways “a lie,” he said, unable to explain the Meissner effect. He gave his own alternative explanation.

Notably, Dr. Hirsch has said that superconductivity is not possible in any high-pressure material because hydrogen cannot be a superconductor. He has gained few allies.

While Dr. Hirsch is careful to say that scientists other than Dr. Dias have committed no wrongdoing, he says they are deceiving themselves.

“In my opinion, the garbage becomes the conclusion,” he said.

Resistance and reproduction

The University of Florida’s Dr Hamlin also delves into the magnetic measurements and says it appears the raw data are derived from published data, not vice versa.

Dr. Hamlin was also disturbed when he discovered that certain passages of his doctoral thesis, written in 2007, appeared, word for word, in Dr. Dias’ thesis.

Dr Dias dismissed the constant criticism and said his team had come up with an explanation. “I just felt like it was just noise from behind,” he said. “We try to keep pushing our science forward.”

He said he still supports previous results and Wednesday’s paper used a new technique to measure magnetism. He said that the paper had undergone five rounds of scrutiny by reviewers and that all raw data underlying the findings were shared.

“It’s back in Nature,” Dr. Dias said. “So that tells you something.”

Sara Miller, a spokeswoman for the University of Rochester, said that after two university investigations, “it was determined that there was no evidence to support the concerns.” She also said that the university had “reviewed the issue of retracting the Nature paper in September 2022 and reached the same conclusion.”

Regarding copying text from Dr. Hamlin’s doctoral thesis, Dr. Dias said he should have included citations. “That was my mistake,” Dr. Dias said.

A reprint of the measurements of the carbon-sulfur-hydrogen material from the retracted 2020 paper is now circulating, but even that raises questions. “They are significantly different from the original measurements,” says Dr. Strobel. “One could argue that they didn’t even reproduce the results themselves.”

Since the new material is based on lutetium that superconducts at much lower pressures, many other research groups will be able to attempt to replicate the experiment. Dr Dias said he wanted to provide a more precise recipe for how to make compounds and share samples, but intellectual property issues need to be addressed first. He founded a company, Excavation Materials, that plans to turn research into a profit.

Dr. Strobel said he will start work as soon as he returns from the Las Vegas conference. “We can literally have results within a day,” he said.

Dr. Hirsch also said he expected answers to come quickly. “If this is true, it proves my work for the past 35 years is wrong,” he said. “Which I will be very happy, because I will know.”

Dr. Hirsch added, “But I think I am right and this is wrong.”

Kimberley McGee Contribution reports from Las Vegas.