Superconductivity of epsilon-Fe: complete resistive transition
  Last year, iron was reported to become superconducting at temperatures below 2K and pressures between 15 and 30 GPa. The evidence presented was a weak resistivity drop, suppressed by a magnetic field above 0.2 T, and a small Meissner signal. However, a compelling demonstration, such as the occurrence of zero resistance, was lacking. Here we report the measurement of a complete resistive transition at 22.2 GPa with an onset slightly above 2 K in two very pure samples of iron, of different origins. The superconductivity appears unusually sensitive to disorder, developing only when the electronic mean free path is above a threshold value, while the normal state resistivity is characteristic of a nearly ferromagnetic metal. 
D. Jaccard (1), A. T. Holmes (1), G. Behr (2), Y. Inada (3), Y. Onuki   (3) ((1) University of Geneva, (2) Institute for Sol...