Scientists sent X-rays through the superconducting material to study its structure.
Photo credits: Courtesy of Drozdov et al.
A superconductor allows electricity to flow perfectly without losing any of it. [1
Let things get cold enough and electrons penetrate metals without generating any resistance, heating or slowing down. This phenomenon, known as superconductivity, has in the past only worked at extremely cold temperatures that are only slightly above absolute zero. This has made them unusable for applications such as extremely efficient electrical wiring or incredibly fast supercomputers. In recent decades, scientists have developed newer superconducting materials that work at ever higher temperatures.
In the new study, a group of researchers came even closer to their goal by creating a material that is superconducting at minus 23 degrees Celsius (minus 9 degrees Fahrenheit) – one of the highest temperatures ever observed.
The team studied a class of materials called superconducting hydrides that are superconducting according to theoretical calculations at higher temperatures. To make these materials, they used a small device called a diamond anvil cell, which consists of two small diamonds that compress materials to extremely high pressures. [The Mysterious Physics of 7 Everyday Things]
They placed a tiny, a few-micron-long sample of a soft, whitish metal called lanthanum in a hole punched into a thin metal foil filled with liquid hydrogen. The structure was connected to thin electrical wires. The device pushed the sample to pressures between 150 and 170 gigapascals, which is more than 1.5 million times the pressure at sea level. They then examined their structure with X-rays.
At this high pressure, lanthanum and hydrogen together form lanthanum hydride.
The researchers found that lanthanum hydride at minus 9 F (minus 23 C) detects two of three properties of superconductivity. The material showed no resistance to electricity and its temperature dropped when a magnetic field was applied. The third criterion, the ability to expel magnetic fields during cooling, they ignored, because the sample was too small, according to an accompanying article by News and Views in the same issue of the journal Nature.
"From a scientific perspective, these results suggest that we could find a transition from the discovery of superconductors to concrete theoretical predictions through empirical rules, intuition, or luck," said James Hamlin, associate professor of physics at the University of Florida who was not part of the study wrote in the comment.
In fact, a group reported similar results in January in the journal Physical Review Letters. These researchers found that lanthanum hydride could be superconducting at an even higher temperature of 44 F (7 C) as long as the sample is subjected to higher pressure – about 180 to 200 gigapascals.
However, this new group found something quite different: at these high pressures, the temperature at which the material shows superconductivity abruptly decreases.
The reason for the discrepancy in the findings is unclear. "In such cases, more experiments, data and independent studies are needed," said senior author Mikhail Eremets, a researcher in high pressure chemistry and physics at the Max Planck Institute for Chemistry in Germany, to Live Science. "Now we can only discuss."
The team now plans to reduce pressure and increase the temperature required to produce these superconducting materials. In addition, researchers continue to search for new compounds that could be superconducting at high temperatures.
The group published its findings yesterday (May 22) in the journal Nature.
Originally published on Live Science .