  We report neutron inelastic scattering measurements on the stoichiometric
iron-based superconductor LiFeAs. We find evidence for (i) magnetic scattering
consistent with strong antiferromagnetic fluctuations, and (ii) an increase in
intensity in the superconducting state at low energies, similar to the resonant
magnetic excitation observed in other iron-based superconductors. The results
do not support a recent theoretical prediction of spin-triplet p-wave
superconductivity in LiFeAs, and instead suggest that the mechanism of
superconductivity is similar to that in the other iron-based superconductors.
