Electrical and thermal transport properties of [formula omitted] compounds, RE=Nd, Gd

Abstract

We report the electrical and thermal transport properties of NdCu4Au and GdCu4Au compounds, crystallizing in the cubic MgCu4Sn - type crystal structure, with space group F4¯3m (no. 216).These properties are reported through measurements of electrical resistivity, ρ(T), thermoelectric power, S(T) and thermal conductivity, λ(T). ρ(T) and S(T) data indicate an antiferromagnetic (AFM)-like anomaly associated with a Néel temperature TN=3.9K and 10.9K for NdCu4Au and GdCu4Au compounds, respectively. ρ(T) data for both compounds shows a sudden drop at TN. Above TN, ρ(T) results are characteristic of an electron–phonon interaction in the presence of s−d scattering. Application of magnetic field slightly suppresses TN value in GdCu4Au compound from TN=10.9K in a field of 0T to 10.1K in a field of 6T. S(T) data at low temperatures for both compounds shows a minimum at TN. Critical analysis of S(T) in terms of the phenomenological resonance model yield the positions (Ef) and bandwidths (Wf) of the 4f - band in both compounds: Ef=3.81(6)K, Wf=329(58)K for the Nd compound and Ef=18.2(4)K, Wf=306(5)K for the Gd compound. λ(T) for both compounds decreases linearly upon cooling from room temperature. The reduced Lorentz number L/L0 deviates from the Wiedmann–Franz at low temperature with a strong increase in L/L0 upon cooling the samples from room temperature.