Scientists discover exotic magnetic structures in iron-based superconductors

Omar Chmaissem
Omar Chmaissem

Scientists from NIU and Argonne National Laboratory are reporting this week in the journal Nature Physics on the discovery of exotic magnetic structures in iron-based superconductors.

Superconductors exhibit amazing properties: When cooled below certain temperatures, they conduct electricity without energy-sapping resistance. But the best known superconducting materials can operate only below 218 degrees Fahrenheit under ambient pressure – and the cooling process itself is expensive.

Today, superconductors are used in Magnetic Resonance Imaging (MRI) devices, in the transportation industry and in scientific-research equipment, including particle accelerators.

But for decades, scientists have been sought to develop higher temperature superconductors, which could revolutionize the energy industry and lead to many more applications, such as powerful supercomputers and devices that now only exist in the imaginations of science fiction writers.

“Unconventional superconductivity, or superconductivity that doesn’t conform to conventional theory, has in recent years been discovered in iron-containing materials,” NIU physicist Omar Chmaissem says.

In the new Nature Physics publication, Chmaissem and NIU physicist Dennis Brown, along with Argonne scientists and NIU graduate physics students Keith Taddei and Matthew Krogstad, report findings that explain the nature of a novel magnetic ground state in iron-based superconductors.

Dennis Brown
Dennis Brown

Understanding the nature of this magnetic ground state is of paramount importance in unveiling the mechanism behind their high-temperature superconductivity, the researchers say.

The research team recently had discovered the existence of a previously-unknown magnetic phase. By combining neutron diffraction and Mössbauer spectroscopy, they were able to unambiguously solve the exotic ordering of the novel magnetic ground state. NIU contributors assumed major roles in the experiment, from the design to execution to data analyses, Chmaissem says.

The textbook-quality results establish the itinerant character of magnetism in iron-based superconductors, and also provide the first conclusive demonstration of metallic magnetism’s wave-like properties.

“Besides its rarity, the importance of this discovery is that it settles a long debated question related to the exact origin of superconductivity in these materials,” Chmaissem says. “Magnetic fluctuations play a primary role in mediating the stability of the superconducting state.”

Print Friendly, PDF & Email