engleski

Doping dependence of the charge distribution of iron pnictides

We have investigated the evolution, on doping, of the charge distribution in the new LaO1− xFxFeAs superconductor. This is done using 75As Nuclear Quadrupole Resonance (NQR), which is a sensitive local probe of the electric field gradient generated by the charge distribution. A significant increase of the quadrupole frequency is observed when going from the undoped situation to the superconducting region of the phase diagram, reflecting the change in density or spatial distribution of the electrons. This increase cannot be properly accounted for by LDA calculations, even though there is good agreement between theory and experience for the undoped case. We discuss this discrepancy as well as the relation to the superconductivity, i.e., the link to the doping-dependence of the critical temperature.

iron pnictides; superconductivity; NQR

nije evidentirano