Revisited magnetic phase diagram for CeNi1-xCux system: spin-glass in the weak interaction limit.

We report the revisited magnetic phase diagram for the Kondo (ferromagnetic and antiferromagnetic) CeNi1−xCux series based on ac–dc magnetization, heat capacity, neutron diffraction and muon spectroscopy down to very low temperatures (~100 mK). An evolution from antiferromagnetism, observed for Cu-rich alloys (0.8 ≤ x ≤ 1), to clustered-ferromagnetism, seen for samples with 0.3 ≤ x ≤ 0.6, and then to spin-glass for 0.1 ≤ x ≤ 0.2, has been observed. The clustered-ferromagnetic phase emerges from a cluster-glass state without any indication of Curie temperature. For the samples adjacent to the magnetic–nonmagnetic crossover 0.1 ≤ x ≤ 0.2, only the cluster-glass state is observed due to the weakening of the RKKY interactions. We discuss the emerging phenomena taking into account the cluster-percolative scenario proposed for this series and the role of the interactions involved along the whole series. The proximity to a T = 0 K spin-glass quantum phase transition in the phase diagram is discussed.