S. Kervan

Magnetic characterization of intermetallic PrMn2Ge2−xSix compounds by AC susceptibility, x-ray diffraction and differential scanning calorimetry studies

X-ray powder diffraction, AC susceptibility and differential scanning calorimetryxa0(DSC) studies were performed on the polycrystalline PrMn2Ge2−xSix () compounds. All compounds investigated crystallize in the body-centred tetragonal ThCr2Si2-type structure with the space group I4/mmm. Substitution of Si for Ge leads to a linear decrease of the lattice constants and the unit cell volume. The lattice constants and the unit cell volume obey Vegards law. Samples in this alloy system exhibit a crossover from ferromagnetic ordering for PrMn2Ge2 to antiferromagnetic ordering for PrMn2Si2 as a function of Si concentration x. At low temperatures, the Pr sublattice also orders for . The samples with are ferromagnetic and have spin reorientation temperatures just below the Curie temperature. In the cases of x = 1.2 andxa01.3, re-entrant ferromagnetism is observed. The samples with are antiferromagnetic below the Neel temperature TN(Mn). By comparing our results to earlier neutron diffraction and Mossbauer studies, the x–T magnetic phase diagram has been constructed.