Transport and magnetic properties of NdCuGe compound

Electrical resistivity, heat capacity, and dc magnetization measurements were performed on the $AlB2$-type intermetallics NdCuGe and LaCuGe over the temperature range of $2–300K$⁠. NdCuGe exhibits magnetization attributable to $Nd3+$ moments, with an antiferromagnetic (AF) transition at $3.1K$⁠. Magnetization, heat capacity, and resistivity measurements were used to determine the crystalline electric field (CEF) splitting of the $Nd3+$ magnetic sublevels. The ground state is a doublet composed of $±5∕2$ levels and the AF state is built from this magnetic doublet, with a reduction in the average sublattice magnetization attributable to site disorder among Cu–Ge sites. Low-temperature electrical transport is dominated by spin-disorder scattering among CEF-split levels and a small $T2$ spin fluctuation term. The latter is nearly two orders of magnitude smaller than previously observed in isostructural CeCuGe, for which the anomalous observed thermopower exponent was attributed to extended spin fluctuations above the magnetic transition. By contrast, simple-metallic behavior provides a good fit to the NdCuGe thermopower, thus, the CeCuGe results can be attributed to resonant scattering due to partial hybridization of the localized orbitals.