Access the latest quantum technology

Quantum technology in Bristol and bath - find out more about how you can access the commercialisation of quantum technology for sensing and security

Thursday, May 23, 2019

Superconductivity moves towards room temperature

By Nick Flaherty www.flaherty.co.uk

Researchers in the US have shown superconductivity at the highest temperatures ever recorded.

The team at the Argonne National Laboratory found a material with superconductivity at temperatures of about -23 degrees Centigrade, 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 toward 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. 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.

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

They used the Advanced Photon Source at Argonne National Laboratory, which provides ultra-bright, high-energy X-ray beams that have enabled breakthroughs in everything from better batteries to understanding the Earth's deep interior, to analyze the material. In the experiment, researchers within University of Chicago's Center for Advanced Radiation Sources squeezed a tiny sample of the material between two tiny diamonds to exert the pressure needed, then used the beamline's X-rays to probe its structure and composition.

Because 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 0 degrees Celsius--seem within reach.

No comments: