Silver sheds light on superconductor secrets

December 20, 2012

The first report on the chemical substitution, or doping, using silver atoms, for a new class of superconductor that was only discovered this year, is about to be published in EPJ B. Chinese scientists from Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, discovered that the superconductivity is intrinsic rather than created by impurities in this material with a sandwich-style layered structure made of bismuth oxysulphide (Bi4O4S3).

Superconductors with a transition temperature (TC) above the boiling temperature of liquid nitrogen (77 kelvins or −196 °C) are called high TC superconductors. In the quest for such materials, compounds with bismuth disulphide (BiS2) layers have recently started to attract a lot of attention. Indeed, in July 2012, Japanese scientists reported achieving a TC at around 4.5 kelvins (-268.65 °C) with the first bismuth oxysulphide superconductor.

All the superconducting samples for this new superconductor reported so far are a mixture of Bi4O4S3 and impurities. However, the pure sample without impurities is not superconducting. Scientists have therefore been wondering whether the observed superconductivity stems from the presence of impurities.

The Hefei team performed systematic measurement of the material's characteristics relying on x-ray diffraction, magnetic susceptibility, electrical transport and thermal transport. Using comparison of the x-ray diffraction patterns, they found that silver atoms partially replace the bismuth sites in the bismuth oxysulphide lattice.

Further experiments involved controlling the composition of the material through various levels of silver doping. The superconductivity, the authors found, was suppressed as the silver content increases and eventually disappears above a certain doping threshold. They believe that it is the modification of electronic structure upon doping that suppresses the superconductivity. Based on these observations, they concluded that the observed superconductivity originates from the bismuth oxysulphide lattice rather than any impurities.
-end-
Reference:

1. S. G. Tan, P. Tong, Y. Liu, W. J. Lu, L. J. Li, B. C. Zhao, Y. P. Sun (2012), Suppression of superconductivity in layered Bi4O4S3 by Ag doping, European Physical Journal B, DOI: 10.1140/epjb/e2012-30975-2

2. Mizuguchi et al. arXiv:1207.3145 [cond-mat.supr-con]

For more information, please visit www.epj.org

The full-text article is available to journalists on request.

Springer

Related Superconductivity Articles from Brightsurf:

New kind of superconductivity discovered
Superconductivity is a phenomenon where an electric circuit loses its resistance and becomes extremely efficient under certain conditions.

Room temperature superconductivity creeping toward possibility
The possibility of achieving room temperature superconductivity took a tiny step forward with a recent discovery by a team of Penn State physicists and materials scientists.

A 'breath of nothing' provides a new perspective on superconductivity
Zero electrical resistance at room temperature? A material with this property, i.e. a room temperature superconductor, could revolutionize power distribution.

New Princeton study takes superconductivity to the edge
The existence of superconducting currents, or supercurrents, along the exterior of a superconductor, has been surprisingly hard to find.

Superconductivity: It's hydrogen's fault
Last summer, it was discovered that there are promising superconductors in a special class of materials, the so-called nickelates.

How a magnet could help boost understanding of superconductivity
Physicists have unraveled a mystery behind the strange behavior of electrons in a ferromagnet, a finding that could eventually help develop high temperature superconductivity.

New study explains why superconductivity takes place in graphene
Theoretical physicists take important step in development of high temperature superconductors.

Better studying superconductivity in single-layer graphene
A new study published in EPJ B demonstrates that an existing technique is better suited for probing superconductivity in pure, single-layer graphene than previously thought.

Stressing metallic material controls superconductivity
No strain, no gain -- that's the credo for Cornell researchers who have helped find a way to control superconductivity in a metallic material by stressing and deforming it.

First report of superconductivity in a nickel oxide material
Scientists at SLAC and Stanford have made the first nickel oxide material that shows clear signs of superconductivity - the ability to transmit electrical current with no loss.

Read More: Superconductivity News and Superconductivity Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.