Superconductivity in the nonmagnetic state of iron under pressure

Ferromagnetism and superconductivity are thought to compete in conventional superconductors, although in principle it is possible for any metal to become a superconductor in its non-magnetic state at a sufficiently low temperature. At pressures above 10GPa, iron is known to transform to a non-magnetic structure(1,2) and the possibility of superconductivity in this state has been predicted(3,4). Here we report that iron does indeed become superconducting at temperatures below 2 K at pressures between 15 and 30 GPa. The transition to the superconducting state is confirmed by both a drop in resistivity and observation of the Meissner effect.