It's here: Scientists have reported the discovery of the first superconductor at room temperature, after more than a century of waiting.
The discovery evokes dreams of futuristic technologies that could reshape electronics and transportation. Superconductors transmit electricity without resistance, allowing current to flow without any loss of energy. But all previously discovered superconductors must be cooled, many of them to very low temperatures, which makes them impractical for most uses.
Now, scientists have found the first superconductor to operate at room temperature, at least with a fairly cold room. The material is superconducting below temperatures of about 15 ° C, physicist Ranga Dias of the University of Rochester in New York and his colleagues report on October 14 in Nature.
The team's results "are nothing short of beautiful," says materials chemist Russell Hemley of the University of Illinois Chicago, who did not participate in the research.
However, the superconducting superpowers of the new material appear only at extremely high pressures, limiting their practical usefulness.
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Days and colleagues formed the superconductor by squeezing carbon, hydrogen, and sulfur between the tips of two diamonds and striking the material with laser light to induce chemical reactions. At a pressure about 2.6 million times that of the Earth's atmosphere and temperatures below about 15 ° C, the electrical resistance disappeared.
That alone was not enough to convince Dias. “I didn’t believe it the first time,” he says. Thus, the team studied additional samples of the material and investigated its magnetic properties.
Superconductors and magnetic fields are known to collide: strong magnetic fields inhibit superconductivity. Indeed, when the material was placed in a magnetic field, lower temperatures were needed to make it superconducting. The team also applied an oscillating magnetic field to the material and showed that when the material became a superconductor, it expelled that magnetic field from its interior, another sign of superconductivity.
Scientists have not been able to determine the exact composition of the material or how its atoms are arranged, so it is difficult to explain how it can be superconducting at such high temperatures. Future work will focus on describing the material more fully, Dias says.
When superconductivity was discovered in 1911, it was only found at temperatures close to absolute zero (-273.15 ° C). But since then, researchers have consistently discovered materials that superconduct at higher temperatures. In recent years, scientists have accelerated that progress by focusing on high-pressure hydrogen-rich materials.
In 2015, physicist Mikhail Eremets of the Max Planck Institute for Chemistry in Mainz, Germany, and colleagues squeezed hydrogen and sulfur to create a superconductor at temperatures down to -70 ° C (SN: 12/15/15). A few years later, two groups, one led by Eremets and another involving Hemley and physicist Maddury Somayazulu, studied a high-pressure compound of lanthanum and hydrogen. Both teams found evidence of superconductivity at even higher temperatures of -23 ° C and -13 ° C, respectively, and in some samples possibly up to 7 ° C (SN: 9/10/18).
The discovery of a room temperature superconductor is no surprise. “Obviously we are heading towards this,” says theoretical chemist Eva Zurek of Buffalo University in New York, who was not involved in the research. But breaking the symbolic room temperature barrier is "a big problem."
If a room temperature superconductor at atmospheric pressure could be used, it could save large amounts of energy lost by resistance in the power grid. And it could improve current technologies, from MRI machines to quantum computers to magnetically levitated trains. Dias predicts that humanity can become a "superconducting society."
But so far scientists have created only small spots of the material at high pressure, so practical applications are still a long way off.
Still, "temperature is no longer a limit," says Somayazulu, of Argonne National Laboratory in Lemont, Illinois, who did not participate in the new research. Instead, physicists now have a new goal: to create a room temperature superconductor that works without tightening, Somayazulu says. "That's the next big step we have to take."
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