Scientists have found that the substitution of cobalt atoms into the crystal framework of an iron-based material—which is required to convert the material from a magnet into a superconductor—also introduces elongated impurity states at each cobalt atom (note the directional alignment of “twin” peaks around each cobalt atom in the electronic structure map). These elongated impurities then scatter electrons in an asymmetric way that explains many of the material’s unusual properties, and could eventually lead to the design of new types of superconductors for practical applications in energy transmission and storage. (Credit: Image courtesy of DOE/Brookhaven National Laboratory)

Dopants Dramatically Alter Electronic Structure of Superconductor

Feb. 17, 2013 — Over the last quarter century, scientists have discovered a handful of materials that can be converted from magnetic insulators or metals into “superconductors” able to carry electrical current with no energy loss — an enormously promising idea for new types of zero-resistance electronics and energy-storage and transmission systems. At present, a key step to achieving superconductivity (in addition to keeping the materials very cold) is to substitute a different kind of atom into some positions of the “parent” material’s crystal framework. Until now, scientists thought this process, called doping, simply added more electrons or other charge carriers, thereby rendering the electronic environment more conducive to the formation of electron pairs that could move with no energy loss if the material is held at a certain chilly temperature.

Now, new studies of an iron-based superconductor by an international team of scientists — including physicists from the U.S. Department of Energy’s Brookhaven National Laboratory and Cornell University — suggest that the story is somewhat more complicated. Their research, published online in Nature Physics February 17, 2013, demonstrates that doping, in addition to adding electrons, dramatically alters the atomic-scale electronic structure of the parent material, with important consequences for the behavior of the current-carrying electrons.

Read more: Dopants dramatically alter electronic structure of superconductor — Science Daily.

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