Magnetic interactions in PrMn2-xCoxGe2

The structure and magnetic properties of PrMn2-xCoxGe2 (0.0less than or equal toxless than or equal to1.0) were studied by X-ray powder diffraction and magnetization measurements. All compounds crystallize in the ThCr2Si2-type structure with the space group 14/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 xless than or equal to0.7, 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 Mossbauer 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 xgreater than or equal to0.8, the antiferromagnetic intralayer alignment of the Mn sublattice occurs below the Neel temperature. The results lead to the construction of the magnetic phase diagram. (C) 2002 Elsevier Science BY. All rights reserved.