In February 2008, an iron-based family of high-temperature superconductors was discovered. Hideo Hosono, of the Tokyo Institute of Technology, and colleagues found lanthanum oxygen fluorine iron arsenide (LaO 1−x F x FeAs), an oxypnictide that superconducts below 26 K. Replacing the lanthanum in LaO 1− x F x FeAs with samarium leads to superconductors that work at 55 K.