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 = 9.5 K) by chemical substitution of Ru, Co and Si. Polycrystalline samples URh1-xRuxGe (x <= 0.6), URh1-xCoxGe (x <= 0.9) and URhGe1-xSix (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) approximate to 0.38. The Curie temperature in the URh1-xCoxGe series has a broad maximum T-C = 20 K near x = 0.6 and then drops to 8 K for x = 0.9. In the case of Si doping T-C stays roughly constant. We conclude that the alloy systems URh1-xRuxGe and URh1-xCoxGe are interesting candidates to study the ferromagnetic instability.