2008/04/30 by T. Nomura, Takatoshi Nomura, Sung Wng Kim +7 · 8 citations
Business, Management and Accounting · Materials Science · Physics and Astronomy · #Corporate Taxation and Avoidance #Iron-based superconductors research #Rare-earth and actinide compounds #cond-mat.supr-con
paper · pdf · doi:10.1088/0953-2048/21/12/125028
published as Supercond. Sci. Technol. 21 (2008) 125028 · 22 pages, 8 figures, 2 tables, Supplementary information is included at the end of the document, accepted for publication in Supercond. Sci. Technol
arxiv created 2008/11/12 · openalex publication_date 2008/11/19 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/04
Undoped LaFeAsO, the parent compound of the newly found high- T c superconductor, exhibits a sharp decrease in the temperature-dependent resistivity at ∼160 K. The anomaly can be suppressed by F doping with simultaneous appearance of superconductivity appears correspondingly, suggesting a close association of the anomaly with the superconductivity. We examined the crystal structures, magnetic properties and conductivity of undoped (normal conductor) and 14 at.% F-doped LaFeAsO ( T c = 20 K) by synchrotron x-ray diffraction (XRD), DC magnetic measurements, and ab initio calculations demonstrated that the anomaly is associated with a phase transition from tetragonal ( P 4/ nmm ) to orthorhombic ( Cmma ) phases at ∼160 K as well as an antiferromagnetic spin ordering transition at ∼140 K. These transitions can be explained by spin configuration-dependent potential energy surfaces derived from the ab initio calculations. The suppression of the transitions is ascribed to interrelated effects of geometric and electronic structural changes due to doping by F − ions.