Scientists break record for highest-temperature superconductor

Washington, PTI | Updated : 29 May 2019, 07:41 AM
Photo for representational purpose only.
Photo for representational purpose only.

Scientists say they have discovered superconductivity -- the ability to conduct electricity perfectly -- at the highest temperatures ever recorded. The researchers at the University of Chicago in the US studied a class of materials in which they observed superconductivity at temperatures of about minus 23 degrees Celsius -- a jump of about 50 degrees compared to the previous confirmed record. Though the superconductivity happened under extremely high pressure, the result still represents a big step towards creating superconductivity at room temperature -- the ultimate goal for scientists to be able to use this phenomenon for advanced technologies.

Just as a copper wire conducts electricity better than a rubber tube, certain kinds of materials are better at becoming superconductive, a state defined by two main properties.

The material offers zero resistance to electrical current and cannot be penetrated by magnetic fields, according to the  results published in the journal Nature.

The potential uses for this are as vast as they are exciting: electrical wires without diminishing currents, extremely fast supercomputers and efficient magnetic levitation trains, said Vitali Prakapenka, a research professor at the University of Chicago.

However, scientists have previously only been able to create superconducting materials when they are cooled to extremely cold temperatures -- initially, minus 240 degrees Celsius and more recently about minus 73 degrees Celsius.

Since such cooling is expensive, it has limited their applications in the world at large.

Recent theoretical predictions have shown that a new class of materials of superconducting hydrides could pave the way for higher-temperature superconductivity.

Researchers at the Max Planck Institute for Chemistry in Germany teamed up with University of Chicago to create one of these materials, called lanthanum superhydrides, test its superconductivity, and determine its structure and composition.

The only catch was that the material needed to be placed under extremely high pressure -- between 150 and 170 gigapascals, more than one and a half million times the pressure at sea level.

Only under these high-pressure conditions did the material -- a tiny sample only a few microns across -- exhibit superconductivity at the new record temperature.

The material showed three of the four characteristics needed to prove superconductivity.

It dropped its electrical resistance, decreased its critical temperature under an external magnetic field and showed a temperature change when some elements were replaced with different isotopes.

The fourth characteristic, called the Meissner effect, in which the material expels any magnetic field, was not detected.

That is because the material is so small that this effect could not be observed, researchers said.

In the experiment, researchers squeezed a tiny sample of the material between two tiny diamonds to exert the pressure needed, then used X-rays to probe its structure and composition.

Since the temperatures used to conduct the experiment is within the normal range of many places in the world, that makes the ultimate goal of room temperature -- or at least zero degrees Celsius -- seem within reach, researchers said.  

First Published: Wednesday, May 29, 2019 07:41 AM
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