Nonmagnetic-magnetic crossover in the URu1-xPdxGa system

X-ray and neutron diffraction, magnetic susceptibility, and magnetization measurements were performed on URu1-xPdxGa solid solutions (x = 0.0-1.0). They crystallize in the hexagonal HoNiAl-type structure with space group P (6) over bar 2m. The concentration dependence of the lattice parameters deviates from Vegard's law, showing anomalies at x = 0.2 and 0.8. The magnetic phase diagram consists of three different concentration regions. Below x = 0.1 the system is nonmagnetic down to 1.7 K. In the region 0.1<x<0.8 the magnetic state of these compositions al higher temperatures can be considered as a ferromagnetic state with a transition temperature T-C that goes through its maximum value of 78.4 K at x=0.5. At lower temperatures this state seems to be more complex and requires further studies. For x greater than or equal to 0.8 the magnetic state of the system also changes with temperature, but the magnetic ground state has been established as antiferromagnetic. The magnetic behavior of the URu1-xPdxGa sold solutions as other similar alloys is governed by a change in both the unit-cell volume and the number of d and/or sp electrons in the system. [S0163-1829(97)06338-8].