Science Daily  November 5, 2021 What distinguishes a superconducting state from a normal state is a spontaneously broken symmetry corresponding to the long-range coherence of pairs of electrons, leading to zero resistivity and diamagnetism. An international team of researchers (Germany, Sweden, Japan, France) was investigating the superconducting metal Ba1-xKxFe2As2 from the class of iron pnictides when they discovered that four electrons instead of two were forming a bond. It was scrutinized for two years using seven different methods to confirm the result. All data were consistent with the same result. Thus, they concluded that the four-particle electron family in certain […]