Magnetic and crystal structure correlations in PrMn1.5Co0.5Ge2: a synchrotron diffraction study

Structure details of PrMn2−xCoxGe2, x=0.5, with the tetragonal ThCr2Si2-type structure have been studied by high-resolution synchrotron powder diffraction. Unit cell parameters a and c, unit cell volume V, c/a, (∂a/∂x)T and (∂c/∂x)T were determined from Rietveld refinements in the temperature range 10–300 K. The average composition 〈x〉=0.49(4) is determined based on a detailed diffraction profile analysis. Our measurements indicate three anomalies in the c/a ratio, (∂a/∂x)T and (∂c/∂x)T at a temperature of about 150 K, which is very close to the transition temperature from antiferromagnetic to ferromagnetic intralayer ordering.