Scientists successfully demonstrate superconductivity at highest temperature till date

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magnetic levitation superconductivity
A high-temperature (liquid nitrogen cooled) superconductor levitating above a permanent magnet. (Credits - Wikimedia Commons)

A group of researchers from the University of Chicago has observed superconductivity at the highest temperature recorded till date. With the help of highly developed technology at the Argonne National Laboratory, affiliated to UChicago, the team observed and studied a group of materials in which superconductivity was detected at a temperature of  -23 degrees Celsius (minus 9 degrees Fahrenheit, 250 K). This is an increase of almost 50 degrees from the previous record.

Although the superconductivity was observed at very high pressure, this observation is a huge step in achieving superconductivity at room temperatures. This is the ultimate goal of researchers using the technologies. The study has been published in the Nature journal. It has been authored by Vitali Prakapenka and Eran Greenberg, researchers at the University of Chicago.

Superconductivity was discovered in 1911 by a Dutch scientist Heike Kamerlingh Onnes. Materials which display superconductivity have two main characteristics, they do not offer any resistance to electricity and magnetic field lines cannot penetrate them. There are a wide range of applications of superconductivity such as high-speed supercomputers and train based on magnetic levitation.

Earlier researchers could only create superconducting materials at very low temperatures such as -240 degrees Celsius and -73 degrees Celsius very recently. It is quite expensive to achieve this level of cooling and thus it limits the application in the real world. Recently, theoretical studies have shown that a new group of materials, the superconducting hydrides can allow for superconductivity at higher temperatures.

Scientists at the Max Planck Institute in Germany and researchers at the University of Chicago collaborated to create such a material, the lanthanum superhydrides and then determined its composition. However for this to be achieved the material had to be placed under high pressures – within 150 and 170 gigapascals which is one and half million times larger than the sea level pressure. Under this large pressure, the material showed superconductivity.

In the experiment, three out of four characteristics to prove superconductivity were exhibited by the material. There was a drop in the electrical resistance and in the critical temperature under the influence of an external magnetic field. It also displayed a change in the temperature when some of the elements were replaced with isotopes. However, it did not show the Meissner effect as the size of the object is very small.

For the experiment, a very small sample of the object was inserted between two diamonds for the needed pressure to be exerted. After that, high energy X-rays from the Advanced Photon Source were used to determine the structure of the material. Scientists are looking for more efficient ways to achieve superconductivity at regular conditions.

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