Electronic band effects on the spin disorder resistivity of Gd4(Co1-xCux)3 compounds

We present a study of the spin disorder resistivity (rho(m infinity)) and the electronic specific heat coefficient (gamma) in Gd-4(Co1-xCux)(3) compounds, with x = 0.00, 0.05, 0.10, 0.20 and 0.30. The experimental results show a strongly nonlinear dependence of rho(m infinity) on the average de Gennes factor (G(av)) which, in similar intermetallic compounds, is usually attributed to the existence of spin fluctuations on the Co 3d bands. Values of gamma were found around 110 mJ mol(-1) K-2 for the Gd-4(Co1-xCux)(3) compounds, much larger than 38.4 mJ mol(-1) K-2 found for the isostructural nonmagnetic Y4Co3 compound. Using a novel type of analysis we show that the ratio rho(m infinity)/gamma(2) follows a well-defined linear dependence on G(av), which is expected when appropriate dependencies with the effective electron mass are taken into account. This indicates that band structure effects, rather than spin fluctuations, could be the main cause for the strong electron scattering and gamma enhancement observed in the Gd-4(Co1-xCux)(3) compounds. A discussion on relevant features of magnetization and electrical resistivity data, for the same series of compounds, is also presented.