Gadolinium spin dilution in the ferromagnetic solid solutions Gd2–x Y x Cu₂Mg

Samples of the solid solution Gd 2– x Y x Cu 2 Mg (in steps of x = 0.2) were synthesized from the elements in sealed tantalum ampoules in a high-frequency furnace. The polycrystalline samples were characterized by X-ray powder diffraction. The structure of Gd 0.988(6) Y 1.012(6) Cu 2 Mg was refined from single-crystal X-ray diffractometer data: Mo 2 B 2 Fe type, P 4/ mbm , a = 762.83(4), c = 375.48(2) pm, w R 2 = 0.0277, 285 F 2 values and 13 variables. Single-crystal data gave no hint for Gd/Y ordering. All samples behave like Curie-Weiss paramagnets with stable trivalent gadolinium and ferromagnetic ordering at low temperature. Within the solid solution the Curie temperature drops almost linearly from T C = 113.5(1) K for Gd 2 Cu 2 Mg to 9.3(1) K for Gd 0.2 Y 1.8 Cu 2 Mg, allowing a precise adjustment of the magnetic ordering temperature through gadolinium spin dilution.