Evolution of ferromagnetic order in URhGe alloyed with Ru, Co and Si

We have investigated the evolution of ferromagnetic order in the correlated metal URhGe (Curie temperature T_C = 9.5K) by chemical substitutionof Ru, Co and Si. Polycrystalline samples URh_1−xRu_xGe (x ≤ 0.6), URh_1−xCo_xGe (x ≤ 0.9) and URhGe_1−xSi_x (x ≤ 0.2) have been prepared and the magnetic properties have been investigated by magnetization and transport experiments. In the case of Ru doping, T_C initially increases, but then decreases linearly as a function of x and is completely suppressed for x_cr ≈ 0.38. The Curie temperature in the URh_1−xCo_xGe series has a broad maximum T_C = 20K near x = 0.6 and then drops to 8K for x = 0.9. In the case of Si doping T_C stays roughly constant. We conclude that the alloy systems URh_1−xRu_xGe and URh_1−xCo_xGe are interesting candidates to study the ferromagnetic instability.