Magnetic structures of RPd2Ge (R = Tb-Er) compounds

Crystal and magnetic structures of RPd2Ge (R = Tb - Er) compounds are determined on the basis of neutron-diffraction data. They crystallize in the orthorhombic Fe3C-type structure (space group Pnma). All the compounds are antiferromagnets. The Neel temperatures are 19 K, 13.5 K, 4.4 K and 3 K for the compounds with Tb, Dy, Ho and Er, respectively. TbPd2Ge and DyPd2Ge undergo a further phase transition in the ordered state and at 1.5 K they exhibit a collinear magnetic structure described by the propagation vector k = (0, 0, 1/2). With increasing temperature the structure changes into a sine-wave-modulated one (at 10 K and 5.5 K for R = Tb and Dy, respectively). HoPd2Ge has a sine-wave-modulated structure and ErPd2Ge is a collinear antiferromagnet at 1.5 K. In both cases the magnetic moments are parallel to the c axis.