We report A 75 s NMR studies on LaFeAs (O1-x Fx) (0≤x≤0.14). At x=0.04 near the phase boundary, from resistivity, spin-lattice relaxation rate 1/ T1, and NMR spectrum measurements, we found weak magnetic order at TN □30 K. Antiferromagnetic (AFM) fluctuations proved through 1/ T1 are suppressed significantly with F doping, and pseudogap behavior without pronounced AFM fluctuations is observed at x=0.11 where TC is maximum. This significant suppression of 1/ T1 T upon F doping while TC remains nearly unchanged suggests that low-energy AFM fluctuations probed with A 75 s NMR do not play a crucial role in the superconductivity.
|Physical Review B - Condensed Matter and Materials Physics
|Published - Jun 11 2009
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics