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nanotimes News in Brief

By measuring how strongly electrons are bound together to form Cooper pairs in an iron-based superconductor, scientists at Brookhaven National Laboratory, Cornell University, St. Andrews Uni- versity, and collaborators provide direct evidence supporting theories in which magnetism holds the key to this material’s ability to carry current with no resistance.

12-04 :: April/May 2012

Image left: Data supports role of magnetism in iron-based su- perconductors: The height of each dot in this image represents the superconducting energy gap – a mea- sure of the strength of electron pairing – for elec- trons moving at a particular momentum (speed in a given direction) on each electronic band (red and yellow rings) of a particular iron superconductor.

The data show that the magnitude of the gap (height of the dots) varies by its momentum (posi- tion along the base plane) and the band it is on – which is exactly what was predicted by theories in which magnetism plays a primary role in the emer- gence of superconductivity. The results therefore strengthen confidence that those theories may help scientists discover or design new superconductors. © BNL

Because the measurements take into account the electronic bands and directions in which the elec- trons are traveling, which was central to testing the theoretical predictions, this research strengthens confidence that this type of theory may one day be used to identify or design new materials with impro- ved properties – namely, superconductors operating at temperatures far higher than today’s.

M. P. Allan, A. W. Rost, A. P. Mackenzie, Yang Xie, J. C. Davis, K. Kihou, C. H. Lee, A. Iyo, H. Eisaki, T.-M. Chuang: Anisotropic Energy Gaps of Iron-Based Superconductivi- ty from Intraband Quasiparticle Interference in LiFeAs, In: Science, Vol. 336(2012), No. 6081, May 04, 2012, Pages 563-567, DOI:10.1126/science.1218726: http://dx.doi.org/10.1126/science.1218726

Two draft guidance documents that address the use of nanotechnology by the food and cosmetics industries were issued by the US Food and Drug Administration.