Oak Ridge National Laboratory scientists used scanning transmission electron microscopy to measure atomic-scale magnetic behavior in several families of iron-based superconductors. (Photo courtesy ORNL)

New measurements of atomic-scale magnetic behavior in iron-based superconductors by researchers at Oak Ridge National Laboratory and Vanderbilt University are challenging conventional wisdom about superconductivity and magnetism.

The study published in Advanced Materials provides experimental evidence that local magnetic fluctuations can influence the performance of iron-based superconductors, which transmit electric current without resistance at relatively high temperatures.

“In the past, everyone thought that magnetism and superconductivity could not coexist,” said ORNL’s Claudia Cantoni, the study’s first author. “The whole idea of superconductors is that they expel magnetic fields. But in reality things are more complicated.”

Superconductivity is strongly suppressed by the presence of long-range magnetism—where atoms align their magnetic moments over large volumes—but the ORNL study suggests that rapid fluctuations of local magnetic moments have a different effect. Not only does localized magnetism exist, but it is also correlated with a high critical temperature, the point at which the material becomes superconducting. [Read more…]