We discovered iron-based layered superconductors: F-doped LaFePnO (Pn = P, As) in 2006. Several superconductors containing square iron lattice have been reported in 2008. Superconducting transition temperature (T c) of F-doped LnFeAsO (Ln = Nd, Sm, ...) reaches ∼55 K. LaFePnO is a 3d transition-metal (T M) based oxypnic-tides: LnT MPnO. The crystal structure is composed of carrier conducting T m-Pn layer and insulating Ln-O layer. Undoped LnFePO (Ln = La, Sm) shows T c ∼3-5 K, while undoped LnFeAsO shows no T c. The undoped LnFeAsO takes an orthorhombic crystallographic phase at temperatures below ∼160 K, F-doping suppresses the structural transition from tetragonal to orthorhombic phase, stabilizing the tetragonal lattice of LnFeAsO. F-doped LnFeAsO with tetragonal symmetry exhibits T c.
|Number of pages||9|
|Journal||Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu|
|Publication status||Published - 2009 Jul 17|
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics