Indian scientists have discovered a new superconductor that provides an alternative path to discover new superconducting materials at higher temperatures, which could lead to a huge reduction in the cost of MRI.
In a first, a four-member team of scientists from the Tata Institute of Fundamental Research (TIFR), Navy Nagar, has discovered superconductivity in Bismuth — the 83rd element in the periodic table. Superconductors are materials that have no resistance to the flow of electricity.
No previous theory has predicted that Bismuth has superconductivity. The BCS or Bardeen-Cooper-Schrieffer theory of superconductivity that won the Nobel Prize in Physics in 1972 for their first microscopic theory on superconductivity does not explain Bismuth to be a superconductor.
“This discovery can show that there can be a new class of superconductors like Bismuth and provide an alternative path to discover new superconducting materials which are totally different from the current superconducting elements,” said professor S Ramakrishnan, lead investigator, department of condensed matter physics and material sciences, TIFR.
The important aspect of the discovery, researchers said, is that unlike other superconducting metallic elements in the periodic table with one mobile electron per atom, Bismuth is distinct. “The concentration of mobile electrons in a semi-metal like Bismuth is extremely low with one mobile electron shared by 1, 00,000 atoms. Since the density is so low, no theory will predict that Bismuth will be a superconductor,” said Ramakrishnan adding that there cannot be immediate spin-offs to the discovery, and that practical application in superconductivity comes 50 to 60 years after the discovery.
For instance, existence of superconducting magnets first came into existence 60 years after Dutch physicist Heike Kamerlingh Onnes of Leiden University discovered superconductivity of mercury in 1911, and was awarded the Nobel Prize.
“It took another 10 years for superconducting magnets to be used initially for laboratory application, in Medical Resonance Imaging (MRI), and in the Large Hadron Collider that discovered the Higgs Boson or God Particle,” said Ramakrishnan.
“This is an experimental feat and just the tip of the iceberg. What is the mechanism of superconductivity in Bismuth is challenging for a theorist like me,” said professor G Bhaskaran, Institute of Mathematical Sciences, Chennai.
“It’s a fantastic discovery coming out of India and will have future implications in spintronics and nanosciences,” he said.
The next step will be to discover Bismuth-like materials that are new superconductors at higher temperatures that can bring about new applications.
“For this, we need a new theory and a new mechanism of superconductivity,” said Ramakrishnan.
The study appeared in Science of the American Association for Advancement of Science on December 1.
Will curb electricity loss
Materials like copper conduct electricity, but these also have some resistance to the flow of electrons that gives rise to heat, and current is lost. There is 30% loss of electricity from the generated point to the supply point because power cables are made of copper.
“This discovery could lead to new superconductors operating at higher temperatures once the new theory is known. Those new superconductors operating above 100 Kelvin will cut down the cost of superconducting magnets so that MRI cost will come down from Rs4,000 to Rs400,” said Ramakrishnan.