NEUTRON-DIFFRACTION STUDY OF UT2X2 (T = MN, FE, X = SI, GE) INTERMETALLIC SYSTEMS

Neutron diffraction and magnetization measurements indicate that, at low temperatures, ferromagnetic ordering is observed in UMn//2Si//2 and UMn//2Ge//2, while UFe//2Si//2 and UFe//2Ge//2 are Pauli paramagnets. The magnetic moments of the U and Mn atoms are aligned along the tetragonal axis. Two critical temperatures of magnetic ordering are observed, the lower one corresponding to the uranium sublattice and the higher one to the Mn sublattice. The stability of magnetic ordering in the U sublattice is discussed in terms of the isotropic RKKY theory. The absence of a magnetic moment of the uranium atoms in the UFe//2X//2 compounds is a result of the strong 5f6d-3d hybridization due to the small interatomic distances.