They discovered that a type of high-temperature superconductor may feature a previously unknown phase of matter that could either work in favor of superconductivity or against it.
Superconductors are usually used in scientific experiments, for example by particle accelerators such as the Tevatron at Fermilab or the LHC at CERN. To reach superconductivity, superconductors are often cooled to absolute zero, which typically requires liquid helium as a coolant. Even high-temperature superconductors need to be cooled halfway to zero. Prior to entering the superconducting phase, electrons are in an energy gap that arises when electrons pair off and drop to the lower energy level, which is the foundation for superconductivity. As soon as the temperature rises, the electrons split up, regain their previous energy level again and a material cannot superconduct anymore as a result.
Stanford's findings suggest that there is another phase in their copper-based superconductor: Many electrons do not pair off, but form an "elusive order" that had not been observed in the past. The researchers said that this state is not understood yet, but further research will highlight whether this phase works in favor of superconductivity or against it. If it is in favor, it can be promoted. If it is against it, it could be suppressed. In the next step, the researchers want to learn to understand the "nature" of this new phase.
The detailed research is published in the March 25 issue of Science.
