Crystal structure and specific heat of GdCuGe

Abstract

A single crystal study of GdCuGe revealed full copper–germanium ordering: NdPtSb type, space group P6₃mc, a=423.2(1), c=753.7(2)pm, wR₂=0.0443, 414 F² values and 10 variables. The copper and germanium atoms build up two-dimensional networks of ordered [Cu₃Ge₃] hexagons with Cu–Ge distances of 244pm. Consecutive [Cu₃Ge₃] layers are rotated by 60° around the perpendicular c-axis with respect to each other. The [Cu₃Ge₃] hexagons show a weak puckering. Heat capacity measurements on the polycrystalline sample of GdCuGe establishes antiferromagnetic ordering around 14K in agreement with reports in the literature. The curves of heat capacity measured in different applied fields crosses each other at two well-defined points exhibiting a behavior usually associated with heavy fermion compounds. The results of the structural analysis and heat capacity measurements are discussed in the light of these interesting observations for a gadolinium intermetallic.