Interplay between doping and pressure effects in magnetism of UCo1-xTxAl (T=Fe, Ni) single crystals

The metamagnetic behavior of UCoAl is easily transformed to ferromagnetism or conventional paramagnetism with doping UCoAl by suitable elements. The new ferromagnetic state is very sensitive to pressure. We demonstrate these phenomena by a magnetization study of the UCo1-xTxAl (T=Fe, Ni) single crystals. The Ni substitution for Co yields an increase of the critical field for the metamagnetic transition. The transition disappears for x=0.10. The UCo0.90Fe0.05Ni0.05Al and UCo0.98Fe0.02Al compounds exhibit ferromagnetism, however, a hydrostatic pressure of only 0.3 GPa is sufficient to suppress ferromagnetic ordering and restore the metamagnetic behavior of UCoAl-type. The ferromagnetism in UCo0.95Fe0.05Al is more stable and persists up to 0.8 GPa