In traditional electrical lines, a significant amount of
energy is lost while the energy travels from its source to homes and businesses
due to resistance. Superconductors, materials that when cooled have zero
electric resistance, have the promise of someday increasing the efficiency of
power distribution, but more must still be learned about superconductors before
they can be widely used for that purpose.
Scientists at the U.S. Department of Energy’s Ames
Laboratory are using specialized techniques to help unravel the mysteries of a
new type superconductor that was discovered in 2008. Ames Lab physicists were
part of an international collaboration that also included scientists at Kyoto University
in Japan, University of Illinois
at Urbana-Champaign, and University of
Bristol in the United Kingdom
to study the materials.
The group found that magnetism may be helping or even
responsible for superconductivity in iron-based superconductors. The results
were published in Science.
“The first step in designing superconductors for new
technologies that will help save energy is better understanding of how
superconductors work,” says Ruslan Prozorov, who led the team at Ames Lab that
also included Kiyul Cho and Makariy Tanatar.
Unfortunately, most conventional measurements of material
parameters, such as resistivity, aren’t useful in the state of
superconductivity. But Prozorov several years ago helped developed a technique
to measure how far the magnetic field penetrates into a superconductor. This
length is called the London
penetration depth, and it reveals basic information about a material, even in
the superconducting state.
“London penetration depth is one of the few quantities we
can measure in a superconducting state to learn more about what’s going on, so
the technique we specialize in here at Ames Laboratory was particularly useful
for this research project,” said Prozorov, who is also an associate professor
of physics and astronomy at Iowa State University. “In this collaboration, we
studied a barium-iron-arsenic-phosphorus material at near zero Kelvin, and our London penetration depth
measurements suggested that magnetism is responsible for superconductivity in
iron-based superconductors. Typically, magnetism is detrimental to
superconductivity, but when it is weakened enough, it might actually be
The international team’s research helps answer one of the
central questions about how iron-based superconductors work.
“Iron-based superconductors may open the door to new energy
technologies,” said Prozorov. “But we’ll only get there through materials
science and understanding the mechanism of superconductivity in these new
Source: Ames Laboratory