Iron-based superconductors

Article By:

Lynn, Jeffrey W. Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland.

Last reviewed:2010

DOI:https://doi.org/10.1036/1097-8542.YB100121

The phenomenon of superconductivity has a rich and interesting history, starting in 1911 when Kamerlingh Onnes discovered that upon cooling elemental mercury to very low temperatures, the electrical resistance suddenly and completely vanished below a critical temperature T_c of 4 K (−452°F). This resistanceless state enables persistent currents to be established in circuits to generate enormous magnetic fields, and to store and transport energy without dissipation. Superconductors have other unique properties, such as the ability to expel and screen magnetic fields and quantum oscillations controlled by the magnetic field that provide extraordinary measurement sensitivity. Over the intervening years, the number of superconducting materials has grown, with higher critical temperatures and improved metallurgical properties, and these have found their way into a number of technological applications, such as magnetic resonance imaging (MRI) systems for the health-care industry. The field was shocked in 2008 by the surprise discovery of a completely new class of superconductors based on iron. These iron-based superconductors have initiated a flurry of activity as researchers try to understand the origin of the superconductivity in these new materials and develop them for potential use in devices. In this latter context, the new materials have quite high (relatively speaking) superconducting transition temperatures (T_c) and rather favorable current-carrying capabilities that should make them useful in practical applications.

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