Superconductivity in oxygen

Among the simple diatomic molecules, oxygen is of particular interest because it shows magnetism at low temperatures. Moreover, at pressures exceeding 95 GPa (similar to 0.95 Mbar), solid molecular oxygen becomes metallic, accompanied by a structural transition(1). The metallization process is characterized by an increase in optical reflectivity(2), and a change in the slope of the resistance-temperature curve(3), Here we report that at pressures of around 100 GPa, solid oxygen becomes superconducting, with a transition temperature of 0.6 K, The transition is revealed by both resistivity measurements and a Meissner demagnetization signal.