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Superconductivity of pure Bismuth crystal at 0.00053 K

Date:
December 2, 2016
Source:
Tata Institute of Fundamental Research
Summary:
The properties of the 83rd element of the periodic table, namely, Bismuth (Bi) have been studied for more than a century and still continues to draw enormous scientific interests due to its anomalous electronic properties.
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The properties of the 83rd element of the periodic table, namely, Bismuth (Bi) have been studied for more than a century and still continues to draw enormous scientific interests due to its anomalous electronic properties.

Bulk rhombohedral Bismuth (Bi) at ambient pressure is a semi-metal and it remains in the normal state down to 0.010 K. Unlike metals where there is roughly one mobile electron per atom, in a semi-metal like Bi, the concentration of mobile electrons is extremely low (100,000 atoms share a single mobile electron).

Hence, the superconductivity (SC) in bulk is thought to be very unlikely due to this extremely low carrier density.

Now, a group of TIFR scientists led by Professor S. Ramakrishnan have discovered superconductivity of a high quality single crystal of Bi (99.998% pure) at 0.00053 K with a critical field of 0.000005 Tesla (nearly 1/8 of earth's magnetic field). The discovery was made by observing a diamagnetic signal using a home made ultra sensitive magnetometer which is housed in a state of the art TIFR copper nuclear refrigerator built in 2011.

This discovery cannot be explained by standard models of superconductivity. A new theory is necessary since the assumption that the electronic (Fermi) energy is much larger than the lattice (vibration) energy used in standard models fails in Bismuth.


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Materials provided by Tata Institute of Fundamental Research. Note: Content may be edited for style and length.


Journal Reference:

  1. O. Prakash, A. Kumar, A. Thamizhavel, S. Ramakrishnan. Evidence for bulk superconductivity in pure bismuth single crystals at ambient pressure. Science, 2016; DOI: 10.1126/science.aaf8227

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Tata Institute of Fundamental Research. "Superconductivity of pure Bismuth crystal at 0.00053 K." ScienceDaily. ScienceDaily, 2 December 2016. <www.sciencedaily.com/releases/2016/12/161202100307.htm>.
Tata Institute of Fundamental Research. (2016, December 2). Superconductivity of pure Bismuth crystal at 0.00053 K. ScienceDaily. Retrieved May 22, 2017 from www.sciencedaily.com/releases/2016/12/161202100307.htm
Tata Institute of Fundamental Research. "Superconductivity of pure Bismuth crystal at 0.00053 K." ScienceDaily. www.sciencedaily.com/releases/2016/12/161202100307.htm (accessed May 22, 2017).

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