CRYSTALLOGRAPHIC DISORDER AND MAGNETISM IN UPD2-XSN

The intermetallic compound UPd2Sn has been shown in previous investiga tions to crystallize in an orthorhombic structure (space group Pnma). No indications for magnetic or superconducting transitions were found. However, if the Pd content is reduced, then, similar to UNi2Sn, a str uctural transition occurs. We prepared UPd1.85Sn and found it to cryst allize as a Heusler compound in the MnCu2Al-structure (space group Fm (3) over bar m). Now the system undergoes a transition into a disorder ed magnetic state at T-mag similar or equal to 28 K. Here, we present our measurements of the specific heat, susceptibility and muon relaxat ion of UPd1.85Sn, and discuss the nature of the magnetic state in rela tion to the crystallographic structure.