Synthesis and magnetic properties of the extended RE 4Pd9Al24 series (RE = Sc, Y, Ce–Nd, Sm, Gd–Lu)

Abstract

Abstract The existing RE 4Pd9Al24 series (triclinic, space group P 1 ¯ $\overline{1}$ ) with RE = Gd–Tm has been extended to the rare earth elements Sc, Y, Ce–Nd, Sm, Yb and Lu. The samples were synthesized from the elements via arc-melting followed by annealing. Phase-purity was checked by powder X-ray diffraction experiments, which were also utilized to refine the lattice parameters. The structure can be described as composed of layers with a stacking of [PtAl2] (A) and [RE 2Al3] (B) slabs in an ABAAB sequence. As two different structure types (P 1 ¯ $\overline{1}$ and R 3 ¯ $\overline{3}$ m) have been reported for this composition, a group-subgroup scheme using the Bärnighausen formalism has been established in order to link the two. The magnetic properties of the X-ray-pure samples were investigated by susceptibility and magnetization measurements. Gd4Pd9Al24 shows the highest transition temperature to antiferromagnetism of T N = 22.0(1) K, however, a broad feature is observed. This is in line with a low-dimensional ordering caused by the layer-like structure and the flat honeycomb arrangement of the Gd atoms.