IIT-K sheds new light on superconductivity in silver-gold alloys

KANPUR: A professor at the Indian Institute of Technology, Kanpur (IIT-K) and his two doctoral students have managed to calculate the superconductivity in the crystals of silver-gold alloys.

In their calculations, the researchers did not find signature of room temperature superconductivity as claimed by Dev Kumar Thapa and Anshu Pandey in their popular preprint repository titled Ag-Au alloys BCS-like Superconductors?.

The calculated superconducting transition temperatures of the silver-gold alloys resulted in Tc (critical temperature) as low as one mK (milli Kelvin). “The research results do not support the experimental observations of Pandey’s team,” professor Dasari LVK Prasad, who worked on the project along with his two doctoral students Surender Singh and Subhamoy Char.

“In fact, the results of our team’s work rather complement with the observations of work of another team of scientists led by Ogale, in where they did not observe any superconductivity in Silver/ Gold modulated nanostructured thin-films grown on Si Quartz substrates by pulsed laser deposition,” said Prasad. In the absence of well-defined

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The technologies based on superconductors will translate into significant benefits to our life, our societies and economies

EUROPEAN COMMISSION’S PRIORITIES

crystal structures of silvergold nano alloys, Prasad’s team have meticulously predicted possible silver-gold alloys’ crystal structures, for which superconductivity has been investigated within the Bardeen–Cooper–Schrieffer (BCS) theory using the stateof-the-art supercomputing facility at IIT-Kanpur and their own in-house High-Performance Computing facility.

According to Prasad, at least in computations, within the BCS formalism, the silvergold alloy systems are found to be very low Tc materials.

“Theoretical studies based on non-BCS mechanisms are therefore extremely important in searching for the emergent superconducting state (if any) in these materials. Of course, further experimental works needs to be done,” Prasad said.

According to Nature.com, superconductors are materials that offer no resistance to electrical current.

Prominent examples of superconductors, include aluminum, niobium, magnesium diboride, cuprates such as yttrium barium copper oxide and iron pnictides.

The European Commission’s priorities says: “Superconductors offer the promise of important major advances in efficiency and performance in electric power generation, transmission and storage; medical instrumentation; wireless communications; computing; transportation and scientific instruments that will result in new paradigms and in societal advances that are cost effective and environmentally friendly.”