Abstract
Undoped LaFeAsO, the parent compound of the newly found high-Tc superconductor, exhibits a sharp decrease in the temperature-dependent resistivity at ∼160K. 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 14at.% F-doped LaFeAsO (Tc = 20K) by synchrotron x-ray diffraction (XRD), DC magnetic measurements, and abinitio calculations demonstrated that the anomaly is associated with a phase transition from tetragonal (P4/nmm) to orthorhombic (Cmma) phases at ∼160K as well as an antiferromagnetic spin ordering transition at ∼140K. These transitions can be explained by spin configuration-dependent potential energy surfaces derived from the abinitio calculations. The suppression of the transitions is ascribed to interrelated effects of geometric and electronic structural changes due to doping by F- ions.
Original language | English |
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Article number | 125028 |
Journal | Superconductor Science and Technology |
Volume | 21 |
Issue number | 12 |
DOIs | |
Publication status | Published - 2008 Dec 1 |
Externally published | Yes |
ASJC Scopus subject areas
- Ceramics and Composites
- Condensed Matter Physics
- Metals and Alloys
- Materials Chemistry
- Electrical and Electronic Engineering