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 ThCr 2Si2-type structure. Substitution of Y for Pr led to a monotonic decre ase in the lattice constants and the unit-cell volume. Samples in this alloy system exhibit a crossover from ferromagnetic ordering for PrMn 2Ge2 to antiferromagnetic ordering for YMn2Ge2 as a function of concen tration. 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 magne tic measurements. Based on the magnetic measurements the tentative mag netic phase diagram showing three concentration regions of qualitative ly different magnetic behaviour has been determined. Increasing substi tution of Y for Pr in PrMn2Ge2 shows a depression of ferromagnetic ord ering and the gradual development of antiferromagnetic ordering. For c ompounds with 0.4 less than or equal to x < 0.7 the magnetization firs t shows a clear ferromagnetic transition at T-C approximate to 330 K, followed by a gradual drop at lower temperature, and then increases ag ain. For compounds with x < 0.4 or x greater than or equal to 0.7, onl y ferromagnetic ordering or antiferromagnetic ordering occurs respecti vely.