The team led by Prof. Anshu Pandey from the institute’s Solid State and Structural Chemistry Unit, claim to have achieved superconductivity at ambient temperature and pressure.

Superconductivity at ambient temperature has been a holy grail in physics. Hence, the IISc team, which has been able to achieve superconductivity at ambient pressure and temperature — 286 K (13°C) — will be a huge breakthrough if the work stands the test of time and other groups succeed in reproducing the results.

“At 286 K we have seen clear transition from a normal state to a superconducting state. This is more than anyone has reported,” says Prof. Arindam Ghosh from the Department of Physics at IISc and a co-author of the paper.

“New video uploaded on diamagnetism at ambient conditions in the newly claimed superconductor. First evidence of magnetic levitation and Meissner effect at room temperature? More updates soon,” Prof. Ghosh, co-author of the paper, tweeted on May 27.

Diamagnetism is one of the important properties of a superconductor. “When a magnetic field is applied from outside, then the superconductor expels magnetic field and never allows magnetic field to go through it. This is used for levitation of a superconductor,” explains Prof. Ghosh. “We were able to achieve diamagnetism at ambient temperature and pressure.”

Still Not Conclusive Enough?

Prof. Pratap Raychaudhuri from the Superconductivity Lab at the Tata Institute of Fundamental Research (TIFR), Mumbai says: “I hope it is superconductivity though this kind of diamagnetism in gold nanoparticles does not necessarily imply superconductivity.”

Prof. Ghosh agrees, and clarifies: “Gold nanoparticles can be diamagnetic, but usually that is much smaller than that of a superconductor. Superconductors are strongest diamagnets in nature. As a result, they experience maximum repelling force from a magnet. Which is probably why we can see the levitation here. There is no report of normal gold nanoparticles being levitated by a magnet.”

The first version posted in arXiv repository on July 23, 2018 by a two-member team of Prof. Anshu Pandey and Dev Kumar Thapa attracted criticism and even questions about the study on the whole. The reason: the presence of identical pattern of noise for two presumably independent measurements of the magnetic susceptibility. Noise, by its very virtue, will be random and so finding nearly identical noise in measurements made under different conditions is highly improbable. Dr. Brian Skinner, a physicist at the Massachusetts Institute of Technology, Boston was the first to notice this.

Interestingly, the plots of magnetic susceptibility versus temperature in the new data still show the repeated “noise” patterns in some instances. In the paper, the researchers have clarified the presence of “noise” patterns: “Noise patterns occur significantly above the instrument noise threshold, and therefore suggest a possible physical origin related to the sample as opposed to instrument artefacts.”

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As published in The Hindu