Magnetic interactions in PrMn 2− xCo xGe 2

Abstract

The structure and magnetic properties of PrMn 2− x Co x Ge 2 (0.0≤ x≤1.0) were studied by X-ray powder diffraction and magnetization measurements. All compounds crystallize in the ThCr 2Si 2-type structure with the space group I4/mmm. Substitution of Co for Mn led to a linear decrease in the lattice constants a and c and the unit cell volume. For samples with x≤0.7, the ferromagnetic interlayer alignment of the Mn sublattice occurs below the Curie temperature. At low temperatures, the rare earth sublattice also orders and rearranges the ordering in the Mn sublattice. By comparing our results to earlier neutron diffraction and Mössbauer studies, it is concluded that the features observed in the temperature dependence of the magnetization above the Curie temperature is related to antiferromagnetic coupling within each Mn layer. For samples with x≥0.8, the antiferromagnetic intralayer alignment of the Mn sublattice occurs below the Néel temperature. The results lead to the construction of the magnetic phase diagram.