Superconductors escape Flatland
Iron-based materials allow 3-D current flow at high temperatures, open new doors for understanding superconductivity
A flat, two-dimensional flow of electric current has long been thought essential to the secret of how high-temperature superconductors work. But new research shows that an iron-based superconductor allows current to flow in three dimensions.
For at least some high-temperature superconductors, the mechanism that enables electrons to flow with zero resistance doesn’t depend on the electrons moving along the boundary between layers in the material, the new research shows. In previous experiments on copper-based superconductors, the free-flowing current always occurred at these 2-D boundaries, so most theorists have thought this 2-Dness is somehow essential to how this category of superconductors works.
Finding a three-dimensional high-temperature superconductor “was very surprising for us,” says Huiqiu Yuan, a condensed matter physicist at Zhejiang University in Hangzhou, China, who coauthored the study published in the Jan. 29 Nature. “The two-dimensionality is not a necessary condition for getting a high superconducting transition temperature.”
These 3-D high-temperature superconductors could also be more useful than their 2-D cousins. When superconducting electric current is confined to a 2-D plane, strong magnetic fields disrupt the current. But superconductors are often used specifically for the purpose of creating strong magnetic fields. This limitation is a major reason why copper-based superconductors haven’t become widely adopted. High-temperature superconductors capable of 3-D flow wouldn’t have the same problem.