Superconductivity in novel sulfur–nitrogen polymer

Can a polymer of sulfur and nitrogen be metallic, even superconducting? Apparently yes, is the answer for polysulfur nitride, $(SN)x$⁠, a highly anisotropic, quasi‐one‐dimensional polymer that looks like a metal, has the transport properties of a metal and becomes superconducting at around 0.3 K. The idea of finding superconductivity in a new part of the periodic table is of course exciting, whether or not practical applications ever arise. So the important questions are the nature of the polymer—its transport properties, crystallographic structure and band structure—as well as speculations about future technological uses. Some of the facts about $(SN)x$ were exchanged and clarified during a special session at the March meeting of The American Physical Society. At that meeting, which took place in Denver from 31 March to 3 April, two groups active in recent studies of the transport properties each described their work. One group is at IBM, San Jose (the group that first saw superconductivity); the other is at the University of Pennsylvania, Philadelphia. A third group actively studying $(SN)x$ is at Temple University (Philadelphia).