image: The iron-based superconductors discovered in 2008 belong to a group of superconductors (see top panel for examples) which exhibit a unique type of "phase diagram" (see the lower panel). In this phase diagram the superconducting phase is adjacent to an "antiferromagnetic" phase in which the magnetic moments form some kind of staggered pattern. An example of such pattern is shown in the inset of the “AF” phase. The precise fashion by which these two phases are connected (the hashed region) can vary from system to system. This commonality makes many researchers feel that Cooper pairing in this group of superconductors is triggered by "antiferromagnetic fluctuations" (i.e. a dynamic form of antiferromagnetism). This is fundamentally different from the pairing mechanism of conventional superconductors where Cooper pairing is caused by lattice vibrations. Significantly the two highest temperature superconductors belong to this “unconventional” group. The “control parameter” in the lower panel can represent the degree of chemical doping, pressure, and more. This image relates to an article that appeared in the April 8, 2011, issue of Science, published by AAAS. The study, by F. Wang of Massachusetts Institute of Technology in Cambridge, Mass., and colleagues was titled, "The Electron-Pairing Mechanism of Iron-Based Superconductors." view more
Credit: Image © <i>Science/</i>AAAS