Alloying and pressure effects on itinerant-electron metamagnetism of the UCoAl-based compounds

With the UCo1-xOsxAl single crystals, we studied interplay between alloying and pressure effects on magnetism of the itinerant electron metamagnet UCoAl. The Os alloying for x ≥ 0.005 switches the UCoAl to ferromagnetism. For the UCo0.995Os0.005Al single crystal, even lowest applied pressure 0.11 GPa is sufficient to suppress ferromagnetism. A sharp metamagnetic transition for various pressures is observed in magnetic fields along the c axis of the crystal. Concentration magnetic phase diagram of the UCo1-xOsxAl, which includes the quantum phase transition from ferromagnetic to metamagnetic state, and P-T-H phase diagram of the UCo0.995Os0.005Al are determined using the data of magnetization measurements at various pressures and temperatures.