Physicists surprised by disappearing and reappearing superconductivity in iron selenium chalcogenide

Superconductivity is a rare physical state in which matter is able to conduct electricity -- maintain a flow of electrons -- without any resistance. This phenomenon can only be found in certain materials at low temperatures, or can be induced under chemical and high external pressure conditions. Research to create superconductors at higher temperatures has been ongoing for two decades with the promise of significant impact on electrical transmission. New work from a team including Carnegie's Xiao-Jia Chen and Ho-kwang "Dave" Mao demonstrates unexpected superconductivity in a type of compounds called iron selenium chalcogenides. Their work is published online by Nature on February 22.