A study of SmMn2−xCoxGe2 (0 ≤ x ≤ 0.4) intermetallics by magnetic measurements

The magnetic properties of SmMn2−xCoxGe2 (0 ≤ x ≤ 0.4) were studied by field-cooled and zero-field-cooled (ZFC) magnetization measurements in the temperature range 5 K ≤ T ≤ 350 K in low external field (50 Oe). Substitution of Co for Mn leads to a linear decrease in the lattice constants a and c, c/a and the unit cell volume V. Co substitution strongly changed the magnetic properties and the magnetic interactions in the Mn sublattice cross over from a ferromagnetic character to an antiferromagnetic one. The results of earlier neutron diffraction, Mössbauer spectroscopy and specific heat measurements on SmMn2Ge2 are also used for interpreting the magnetization data and to give an account of the competing effects between various magnetic structures in the Mn and Sm sublattices.