engleski

Electronic properties of iron pnictides in the normal state probed by NMR

We have performed 75As, 139La, and 57Fe Nuclear Magnetic Resonance (NMR) measurements on the new LaO1− xFxFeAs superconductor. For x=0.1, NMR on all three nuclei shows that the local electronic susceptibility increases with increasing temperature in the normal state. The scaling of all NMR shifts with respect to the macroscopic susceptibility indicates a single spin liquid. Relaxation measurements exhibit a similar temperature-dependence for (T1T)− 1, and suggest that the dynamical susceptibility changes uniformly in q space with varying temperature. For x=0.05, in the underdoped regime, we find a Curie Weiss like increase of (T1T)− 1 at low temperatures, indicating the onset of local moment fluctuations.

iron pnictides; NMR

nije evidentirano