Search for a critical concentration from ferromagnetic to antiferromagnetic ground state in CeRu 2(Si 1− xGe x) 2

Abstract

Thermal expansion, magnetization, and magnetostriction experiments performed on CeRu 2(Si 1− x Ge x ) 2 single crystals with 0.55⩽ x⩽1 are reported. An antiferromagnetic (AF) ordering is always observed ( T N=8.3 and 10.1 K for x=1 and 0.55, respectively). For x=0.7 a ferromagnetic (FM) transition occurs. T C decreases rapidly from 7.5 K for x=1, to 3 K for x=0.7 and the AF area in the ( B, T ) plane increases. The ground state remains AF for (0.06–0.07) ⩽ x⩽0.6. A crystal with x=0.65 should show T C=0.