2D crystal structure and anisotropic magnetism of GdAuAl (x ≈ 0.54).

Exploration of the gold-rich part of the ternary Gd-Au-Al system afforded the intermetallic compound GdAuAl (x ≈ 0.54) which was structurally characterized by single crystal X-ray diffraction (Pnma, a = 18.7847(4) Å, b = 23.8208(5) Å, c = 5.3010(1) Å). GdAuAl crystallizes in a previously unknown structure type featuring layers of Gd(Au, Al) and Gd(Au, Al) clusters which are arranged as in a close-packing parallel to the ac plane. The Gd substructure corresponds to slightly corrugated 3 nets (d = 5.30-5.41 Å) which are stacked on top of each other along the b direction with alternating short (5.4, 5.6 Å, within layers) and long distances (6.4 Å, between layers). The title compound has been discussed with respect to a quasicrystal approximant (1/1 AC) GdAuAl in the same system. The magnetic properties of GdAuAl were found to be reminiscent to those of some ternary ACs, with sharp peaks in the temperature dependent magnetization, and metamagnetic-like transitions. The material becomes antiferromagnetic below 25 K; magnetometry results suggest that the antiferromagnetic state is composed of ferromagnetic ac planes, coupled antiferromagnetically along the b direction.