Probing of the charge distribution in iron pnictides

A powerful tool to probe the electronic charge distribution in correlated oxides is nuclear magnetic/quadrupole resonance (NMR/NQR). Indeed, through sensitivity to the electric field gradient (EFG), NMR/NQR allows to probe locally the symmetry of the charge distribution, its homogeneity, as well as its sensitivity to structural and doping changes. In context of our own results, we discuss here the state of knowledge in iron pnictides. It appears that the iron pnictides feature a complex behaviour of their charge distribution, with a non-trivial link between the measured EFG and the structural and doping variations.