Researchers' find may help improve superconductors

A team of Chinese and U.S. scientists have made a discovery involving two iron-based compounds that could inch them nearer toward better superconductors.

Researchers led by physicist Si Qimiao at Rice University found two classes of iron compounds, pnictides and chalcogenides, adopt similar coupling between electrons in their superconducting state. This would help scientists identify ways to improve superconductivity, which Si described as the ability of electrons to travel through a material with no resistance and producing no heat. Such efforts have been challenging, but any breakthroughs would bring about revolutions in power generation and distribution, as well as transportation, computing, and medical imaging, he explained. 

He noted that superconductors must be made of the right materials, with electrons in the right state. These would depend on the temperature and how atoms within the materials used coordinated their activities. 

The latest discovery of the two iron compounds helped the scientists define the interplay of energies, superconducting transition temperature, and electron spin responsible for magnetism, Si noted. 

He explained that, historically, magnetism had been deemed detrimental to superconductivity. However, the discovery involving iron pnictides and chalcogenides, among other materials, indicated magnetism often went hand-in-hand with superconductivity. So the scientists sought to identify the circumstances under which this electron coupling would result in optimized superconductivity. 

"Ironically, this regime of electron correlation produces poor electrical conduction above the superconducting transition temperature, so the optimized superconductivity arises out of a bad metal," said Yu Rong, a co-author of the paper which details the discovery. Yu is an associate professor at Renmin University in Beijing, and was a postdoctoral fellow at Rice.