Scientists at the Argonne National Laboratory have discovered a unknown phase in a class of superconductors called iron arsenides that may be able to harness their energy efficient power transmission capabilities for a wide range of new technologies.
The discovery sheds light on a debate over the interactions between atoms and electrons responsible for their unusual superconductivity. This new magnetic phase, which has never been observed before, could have significant implications for our understanding of unconventional superconductivity, explained Ray Osborn, an Argonne physicist and coauthor on the paper entitled "Magnetically Driven Suppression of Nematic Order in an Iron-Based Superconductor," which has been published in Nature Communications.
"Neutron diffraction from a polycrystalline sample of BaFe2As2 with sodium doped onto 24% of the barium sites. The panels show how the intensity of three diffraction peaks vary with temperature as the atomic and magnetic structures change. These structures are shown schematically on the right, with the blue balls representing iron atoms and the red arrows the direction of their magnetic moments." Read more »
(Source: Image by Jared Allred/Argonne National Laboratory.)
Superconductors are capable of carrying electric current without any resistance, as compared with good conductors such as the copper wires used in most power cords that lose energy along the way. Superconductors are not currently used for power transmission lines because they need to be cooled to extremely cold temperatures to be effective. However, a specific range of "unconventional superconductors" may offer better prospects. The Argonne researchers believe that by figuring out the theory behind how unconventional superconductors operate it may possible to raise the temperature at which they work, thereby harnessing their power for a wide range of new technologies.
The theory behind older, conventional superconductors is fairly well understood. Pairs of electrons, which normally repel each other, instead bind together by distorting the atoms around them and help each other travel through the metal. (In a plain old conductor, these electrons bounce off the atoms, producing heat). In unconventional superconductors the electrons still form pairs, but we do not know what binds them together.