Magnetic ordering in PrT2Ge2 (T = Ni, Ru and Rh) compounds

X-ray and neutron diffraction, magnetization, magnetic susceptibility and electrical resistivity measurements were performed on polycrystalline samples of PrNi2Ge2, PrRu2Ge2 and PrRh2Ge2. All the investigated compounds crystallize with a tetragonal structure of the ThCr2Si2-type. All of them exhibit metallic-like electrical conductivity and order magnetically at low temperatures, namely PrNi2Ge2 and PrRh2Ge2 are antiferromagnetic below TN = 23.5 and 45 K, respectively, while PrRu2Ge2 is a ferromagnet with TC = 14.8 K. The neutron diffraction data indicated a modulated antiferromagnetic structure in PrNi2Ge2 in the entire ordered region. For PrRh2Ge2 a collinear antiferromagnetic ordering was derived below Tt = 30 K and a sine-modulated ordering above that temperature. The neutron diffraction corroborated a simple ferromagnetic structure in PrRu2Ge2.