Cu-doping effects on the ferromagnetic semimetal CeAuGe

•Polycrystalline samples of CeAu1-xCuxGe (0.0 ≤ x ≤ 1.0) were synthesized by arc-melting method.•CeAu0.5Cu0.5Ge exhibits the highest Curie temperature of 12 K.•By using symmetry analysis, the solutions for the magnetic structure in the ferromagnetic Shubnikov space groups were found.•Electrical resistivity shows a metallic behaviour for 0.0 ≤ x ≤ 1.0 and Kondo effects for x = 0.8, 1.0.•Low-temperature transition feature of electrical resistivity was observed in the ferromagnetic state for x = 0.2. We present a study of Cu-substitution effects in 4f-Ce intermetallic compound CeAu1-xCuxGe, with potentially unusual electronic states, in the whole concentration range (x = 0.0 – 1.0). The parent CeAuGe compound, crystallizing in a non-centrosymmetric hexagonal structure, is a ferromagnetic semimetal with Curie temperature 10 K. Cu-doping on Au-site of CeAuGe, CeAu1-xCuxGe, changes the crystal structure from the non-centrosymmetric (P63mc) to centrosymmetric (P63/mmc) space group at the concentration x ∼ 0.5, where the c-lattice constant has a maximum value. Magnetic susceptibility and electrical resistivity measurements reveal that all Cu-doped compounds undergo magnetic phase transition near 10 K, with the maximum transition temperature of 12 K for x = 0.5. The neutron powder diffraction experiments show the ferromagnetic ordering of Ce3+ magnetic moments with a value of about 1.2 μB at 1.8 K, oriented perpendicular to the hexagonal c-axis. By using symmetry analysis, we have found the solutions for the magnetic structure in the ferromagnetic Shubnikov space groups Cmc'21′ and P21′/m' for x