Nano Science and Technology Institute

Dopants Dramatically Alter Electronic Structure of Superconductor

February 21, 2013 09:04 AM EST By: Jennifer Rocha

Findings explain unusual properties, but complicate search for universal theory

Story content courtesy of Brookhaven National Laboratory, US

New studies of an iron-based superconductor have been conducted by an international team of scientists - including physicists from the U.S. Department of Energy’s Brookhaven National Laboratory and Cornell University.  Their recently published research 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.

“The key observation - that dopant atoms introduce elongated impurity states which scatter electrons in the material in an asymmetric way - helps explain most of the unusual properties,” said J.C. Séamus Davis, the study’s lead author, who directs the Center for Emergent Superconductivity at Brookhaven Lab and is also the J.G. White Distinguished Professor of Physical Sciences at Cornell University. “Our findings provide a new starting point for theorists trying to grapple with how these materials work, and could potentially point to new ways to design superconductors with improved properties,” he said. 

The researchers used a technique developed by Davis called spectroscopic imaging scanning tunneling microscopy to visualize the electronic properties around individual dopant atoms in the parent material, and to simultaneously monitor how electrons scatter around these dopants (in this case, cobalt). 

Brookhaven’s role in this research was supported by the Center for Emergent Superconductivity, a DOE Energy Frontier Research Center headquartered at Brookhaven National Laboratory. Additional funding was provided by the DOE Office of Science (Ames Laboratory), the National Science Foundation, the U.K. Engineering and Physical Sciences Research Council, the Scottish Funding Council, and the Netherlands Organization for Scientific Research.

 

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