Evolution of magnetism in U(Ni $\scriptstyle \mathsf {}$ 1- x Pd $\scriptstyle \mathsf {}$ x ) $\scriptstyle \mathsf {2}$ Si $\scriptstyle \mathsf {2}$ single crystals

Abstract

Single crystals of U(Ni1-xPdx)2Si2 with x = 0.05, 0.09 and 0.135 have been grown. Magnetization and electrical resistivity measurements were performed in a wide range of temperatures and magnetic fields in order to study stability of magnetic phases in the solid solutions between UNi2Si2 and UPd2Si2 with a special emphasis on the type of ground state. In UPd2Si2 the simple AFI-type antiferromagnetic structure of U moments is observed at low temperatures. UNi2Si2 adopts the uncompensated AF structure (UAF) with the + + - stacking of U moments along the c-axis and consequently this compound exhibits a spontaneous magnetization corresponding to 1/3 of the U moment. The substitution of Pd for Ni leads to a rapid decay of the spontaneous magnetization. The evolution of magnetization and electrical resistivity behavior with Pd doping is tentatively attributed to the coexistence of the AF-I and UAF phases in the ground state of U(Ni0.91Pd0.09)2Si2 and U(Ni0.865Pd0.135)2Si2. In this scenario, the volume fraction of the AF-I phase rapidly grows with Pd doping on account of the UAF. At lowest temperatures an irreversible transition to the UAF phase is observed when a sufficiently high magnetic field is applied along the c-axis.