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

Abstract

We have investigated the evolution of ferromagnetic order in the correlated metal URhGe (Curie temperature $T_{\mathrm{C}}=$9.5 K) by chemical substitution of Ru, Co and Si. Polycrystalline samples URh${}_{1-x}$Ru${}_x$Ge ($x\le$0.6), URh${}_{1-x}$Co${}_x$Ge ($x\le$0.9) and URhGe${}_{1-x}$Si${}_x$ ($x\le$0.2) have been prepared and the magnetic properties have been investigated by magnetization and transport experiments. In the case of Ru doping, $T_{\mathrm{C}}$ initially increases, but then decreases linearly as a function of $x$ and is completely suppressed for $x_{\mathrm{cr}}\approx 0.38$. The Curie temperature in the URh${}_{1-x}$Co${}_x$Ge series has a broad maximum $T_{\mathrm{C}}=20$ K near $x=0.6$ and then drops to 8 K for $x=0.9$. In the case of Si doping $T_{\mathrm{C}}$ stays roughly constant. We conclude that the alloy systems URh${}_{1-x}$Ru${}_x$Ge and URh${}_{1-x}$Co${}_x$Ge are interesting candidates to study the ferromagnetic instability.

15 pages, 12 figures; revised & shortened version