AsianScientist (Dec. 6, 2016) – Researchers in India have discovered that a high-quality single crystal of bismuth can act as a superconductor. Their discovery was published in Science.
Superconductivity is a phenomenon that occurs when there is exactly zero electrical resistance in a substance, and is observed when some materials are cooled below critical temperature. Unlike metals, where there is roughly one mobile electron per atom, the concentration of mobile electrons is extremely low in a semi-metal like bismuth—100,000 atoms share a single mobile electron, making superconductivity in bulk rhombohedral bismuth very unlikely.
Now, a group of scientists from the Tata Institute of Fundamental Research, led by Professor S. Ramakrishnan, have discovered superconductivity of a single crystal of bismuth that is 99.998 percent pure, at 0.00053 Kelvins (approximately -273°C), with a critical field of 0.000005 Tesla—nearly one-eighths of Earth’s magnetic field. The discovery was made by observing a diamagnetic signal using a home-made ultra sensitive magnetometer.
This discovery cannot be explained by the standard models of superconductivity, the researchers say. A new theory is therefore necessary, since the assumption that electronic energy is much larger than the lattice energy, used in standard models, fails in bismuth.
The article can be found at: Prakash et al. (2016) Evidence for Bulk Superconductivity in Pure Bismuth Single Crystals at Ambient Pressure.
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Source: Tata Institute of Fundamental Research; Photo: Pixabay.
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