Atomic Magnetic Moment and Exchange Interaction between Mn Atoms in Intermetallic Compounds in Mn-Ge System

Magnetic properties of four intermetallic compounds, ε, ε 1 , κ and η, in manganese-germanium system are studied by means of magnetization measurement and neutron diffraction. Exchange coefficients of the interaction between Mn atoms in the compounds are estimated quantitatively using the molecular field approximation, based on the localized moment model. The exchange coefficient between Mn atoms on different sublattices is found to depend largely on the interatomic distance: The exchange coefficient is found to be negative for smaller interatomic distances than r c =2.9 Å and positive for larger distances. The magnitude of atomic magnetic moment in the compounds is consistently discussed using the Pauling valence, after Môri and Mitsui (J. Phys. Soc. Jpn. 25 (1968) 82).