Electronic properties of UCoAl0.75Sn0.25 single crystal

A single crystal of the UCoAl0.75Sn0.25 quasiternary compound has been grown and studied by measuring the magnetization, specific heat and electrical resistivity at various temperatures and magnetic fields. Similar to the parent compounds UCoAl and UCoSn, the magnetization of their solid solution exhibits uniaxial anisotropy with a strong magnetic response along the c-axis and a weak and nearly temperature independent paramagnetic signal in the basal plane. The evolution of the c-axis magnetization isotherms, as well as the anomalies in the temperature dependence of the specific heat and resistivity point to ferromagnetism in UCoAl0.75Sn0.25 below TC∼5.5 K. The low value of the spontaneous magnetic moment, poor saturation of the magnetization, the pronounced negative magnetoresistance with increasing magnetic field and the temperature and magnetic field dependence of specific heat provide indications of strong fluctuations of the U magnetic moment also in the ferromagnetic state