M ssbauer spectroscopy of iron-based superconductors

A brief review concerned with the application of the M ssbauer spectroscopy to the investigations of iron-based superconductors is given. An introduction is devoted to the description of the most important features of the M ssbauer spectroscopy followed by the discussion of the basic properties of iron-based superconductors. Our results obtained for FeSe, LiFeP and parent compounds of the ‘122’ family, i.e., for AFe2As2 (A=Ca, Ba, Eu) are discussed later on with particular attention paid to the spin density wave (SDW) magnetism exhibited by the parents of the ‘122’ family. It is found that incommensurate SDW contain many harmonics in these layered structures and evolve from almost separated magnetic sheets through quasi-triangular forms to almost rectangular shape with the lowered temperature.