Evolution of the magnetic phase diagram in CeRu2(Si1-xGex)(2)

The variations of the ordering temperatures and of the magnetic (B, T) phas e diagram for single crystals of the system CeRu2(Si1-xGex)(2) are reported . An antiferromagnetic (AF) ground state occurs for x greater than or simil ar to 0.06. At first, the Neel temperature T-N increases rapidly with x, an d the (B, T) diagram contains three AF phases. The ground state remains AF up to x approximate to 0.6. T-N is maximum (approximate to 10 K) for x = 0. 5. However, the (B, T) diagram becomes simpler: only the low field AF phase subsists for x = 0.55. A ferromagnetic ground state is observed for x = 0. 7 like in CeRu2Ge2 itself. Te increases rapidly with x and T-N slightly dec reases whereas the area of the AF phase between T-C and T-N shrinks. (C) 19 99 Elsevier Science B.V. All nights reserved.