Competition between the screening effect and exchange interactions in the system CeCu$_{1-x}$Al$_{x}$Ge*

As revealed in the powder $x$-ray diffraction and crystallographic data, the single phase sample in the series CeCu$_{1-x}$Al$_{x}$Ge (0.1\textless $x$\textless 0.5) crystallizes in the PuGa$_{2}$-type structure with space group P6/mmm. The substitution of Cu by Al in CeCu$_{1-x}$Al$_{x}$Ge, which increases the average conduction electron density, was found to be able to attenuate the localized Ce-4f moments. As determined from the electrical-resistivity and magnetic susceptibility measurements, both the ferromagnetic transition temperature T$_{c}$ value and the magnitude of the saturation moment in the series CeCu$_{1-x}$Al$_{x}$Ge reflect the decreasing strength of exchange interactions with the Al concentration. These results suggest that the screening effect surpasses the RKKY interactions in this system.