Magnetic properties of Pr1-xYxMn2Ge2 compounds

The structure and magnetic properties of the Pr1-xYxMn2Ge2 compounds (x = 1.0) have been investigated. All the compounds crystallize in ThCr2Si2-type structure. Substitution of Y for Pr led to a monotonic decrease in the lattice constants and the unit-cell volume. Samples in this alloy system exhibit a crossover from ferromagnetic ordering for PrMn2Ge2 to antiferromagnetic ordering for YMn2Ge2 as a function of concentration. The low-temperature behaviours of samples in the range 0 less than or equal to x less than or equal to 1.0 were studied using magnetic measurements. Based on the magnetic measurements the tentative magnetic phase diagram showing three concentration regions of qualitatively different magnetic behaviour has been determined. Increasing substitution of Y for Pr in PrMn2Ge2 shows a depression of ferromagnetic ordering and the gradual development of antiferromagnetic ordering. For compounds with 0.4 less than or equal to x < 0.7 the magnetization first shows a clear ferromagnetic transition at T-C approximate to 330 K, followed by a gradual drop at lower temperature, and then increases again. For compounds with x < 0.4 or x greater than or equal to 0.7, only ferromagnetic ordering or antiferromagnetic ordering occurs respectively.