Trapping vortices key to high-current superconductors

If we are to see the promised benefits of high-temperature superconductors, such as low-loss motors and generators or maglev trains, we will need superconductors that can carry very large currents. Decades-old experiments have shown that the current density a superconductor can carry may be increased by bombarding the material with high-energy ion beams. But to engineer such materials on a large scale, we need to know what's actually happening in the lab samples. The emerging technology of the scanning tunneling microscope (STM) has finally provided a picture at the atomic level that may lead to a theory to guide future engineers. Researchers at Cornell and Brookhaven and Argonne national laboratories have found that irradiation of the material creates nanometer-sized defects that trap swirling eddies in the flow of electrons, keeping them out of the way so more current can flow. They reported their discovery in the May 22 issue of the journal Science Advances. "No previous experiment has ever imaged the effects of such damage on the atomic scale electronic structure of any material," said J.C. Séamus Davis, the James Gilbert White Distinguished Professor in the Physical Sciences and director of the Center for Emergent Superconductivity at Brookhaven.