Materials and Novel Superconductivity in Iron Pnictide Superconductors

Since the first report on superconductivity at 26 K in F-doped LaOFeAs at the end of February 2008, the iron pnictide superconductor family has been quickly expanded to six different structures, and the superconducting transition temperature has been rapidly raised to approximately 57 K. Meanwhile, the pairing mechanism has been clarified as nonconventional, and the antiferromagnetic (AF) spin fluctuations (SFs) seem to play important roles in making these pairs. This article covers a brief overview of the materials and novel superconductivity in this fascinating field, including issues concerning the materials and structures, phase diagram, pairing symmetry, and spin excitations. We give perspectives on these topics and raise questions instead of simply summarizing the theoretical and experimental achievements about the superconducting mechanism.