Neutron scattering studies on LiFeAs and BaFe$_{2}$As$_{2}$

The anisotropy of the magnetic excitations in BaFe$_{2}$As$_{2}$ was studied by polarization analysis. We find the in-plane polarized transverse magnon to lie at higher energy than the out-of-plane polarized one indicating very strong in-plane single-ion anisotropy. Superconducting LiFeAs exhibits the suppression of local susceptibility expected for spin-singlet pairing. Inelastic correlations appear in LiFeAs at the incommensurate wave vectors, they respond to the opening of the superconducting gap by a transfer of spectral weight.