By Josh Perry, Editor
[email protected]

Scientists at the Massachusetts Institute of Technology (MIT) are studying ceramic copper oxides, including yttrium barium copper oxide, with a cryogenic optical spectrometer to see how the materials react to high current in the hope of increasing their technological applications.

Riccardo Comin (left), an assistant professor of physics, and physics graduate student Abraham Levitan assemble the contacts on a sample holder that they’ll use to study the effects of high current on the superconducting material yttrium barium copper oxide.
(Denis Paiste/Materials Research Laboratory)

Superconductors are highly-efficient conductors of current, according to the report from MIT, which have numerous applications. The materials can store large electrical currents without dissipating large amounts of heat, but they also require being cooled to ultra-low temperatures.

“Because superconductors can sustain very large currents, they can store a lot of energy in a relatively small volume,” the article explained. “But even superconducting materials cannot sustain limitless electrical currents, and they can lose their special properties above a critical current density, which is in excess of 10 mega-amperes per square centimeter for state-of-the-art superconducting cables. By comparison, copper can carry a maximum current density of 500 amperes per square centimeter, which is same as the current density passed through a 100-watt tungsten wire light bulb.”

While scientists know about the current limit, the nanoscale interactions creating this cut-off point are not well understood. MIT researchers are working with large currents through yttrium barium copper oxide, which can be used at higher temperatures than other super conductors (77 kelvins or -320.4°F) but is also more easily damaged than materials such as niobium-tin alloys.

“Although superconductivity takes over at liquid nitrogen temperature, as the material is subjected to larger and larger electric fields, other electronic states, or phases, such as a charge density wave, begin to compete with superconductivity before it ceases,” the article noted.

“The ultimate goal of this research effort is to elucidate how a persistent current, or supercurrent, flows around non-superconducting regions hosting competing phases, when the latter start to proliferate near critical conditions.”

Read the full article at http://news.mit.edu/2018/mit-riccardo-comin-making-better-superconductors-from-ceramic-copper-oxides-1213.