The superconductivity at 18 K in LiFeAs system

The recent discovery of superconductivity in iron arsenide compounds RFeAsO (R=rare earth) or AFe2As2 (A=alkaline earth) has attracted great attention due to the unexpected high T c in the system containing ferromagnetic elements like Fe. Similar to high T c cuprates, the superconductivity in iron arsenide is related to a layered structure. Searching for new superconductors with [FeAs] layer, but of simpler structure will be of scientific significance either to build up new multilayered superconductors that may reach higher T c or to study the mysterious underlined superconducting mechanism in iron arsenide compounds. Here we report that a new superconducting iron arsenide system LiFeAs was found. The compound crystallizes into a structure containing [FeAs] conducting layer that is interlaced with Li charge reservoir. Superconductivity was observed with T c up to 18 K in the compounds.