Magnetic and Structural Features of Rare Earth Intermetallic Compounds as Seen by 57Fe Moessbauer Probe

57Fe Moessbauer spectroscopy has been used to study the magnetic structure of some intermetallic compounds having strongly correlated electronic properties including some magnetic superconducting compounds. The common characteristic of the presently studied systems is the fact that they have a crystalline structure closely related to the ThCr2Si2- and BaNiSn3-type of structures, where the transition metal carries no magnetic moment. This specific property allows using 57Fe as Moessbauer probe located at the transition metal site to detect very small transferred hyperfine fields (Bthf) from the neighboring rare earth sites, and in many cases, to determine the angle θ between Bthf and the z-axis component of the electric field gradient (EFG).