Johns Hopkins University researchers and colleagues in China have unlocked some of the secrets of newly discovered iron-based high-temperature superconductors, research that could result in the design of better superconductors for use in industry, medicine, transportation and energy generation. In an article published this week in the journal Nature, the team, led by Chia-Ling Chien, director of the Hopkins Material Research Science and Engineering Center, offers insights into the stunning implications of this new family of superconductors. “It appears to us that the new iron-based superconductors disclose a new physics, contain new mysteries and may start us along an uncharted pathway to room temperature superconductivity,” said Chien, whose lab teamed up researchers from the Hefei National Laboratory for Physical Science at Microscale, based at the University of Science and Technology of China in Anhui.

Today, superconductors are used in hospital MRI machines, as filters in cell phone base stations, and in high-speed magnetic levitating trains. Unfortunately, most superconducting materials can only function and operate at extremely low temperatures, which means they must be paired with expensive supercooling equipment. This presents researchers with a grand challenge: to find superconducting material that can operate at a more “normal” temperature. “If superconductors could exist at room temperatures, the world energy crisis would be solved,” Chen said. Though all metals contain mobile electrons which conduct electricity, a metal becomes a superconductor only when two electrons with opposite “spins” are paired. The superconductor energy “gap,” which is the amount of energy that would be needed to break the bond between two electrons forming such a pair, determines the robustness or strength of the superconducting state. This energy gap is highest at low temperatures, but vanishes at higher temperatures. The team measured this gap and its temperature variation, revealing that the pairing mechanism in iron-based superconductors is different from the one in more traditional, copper-based, high-temperature superconductors. To the researchers’ surprise, their results were incompatible with some of the newly proposed theories in this mushrooming field. Go to: Headlines@Hopkins

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