Gadolinium spin dilution in the solid solution Gd_1–xY_xAuMg – gradual decrease of the Néel temperature

Abstract

Dedicated to Professor Josef Breu on the Occasion of his 60 th Birthday.The intermetallic compounds GdAuMg and YAuMg form a continuous solid solution Gd 1-x Y x AuMg. Samples in x = 0.1 steps were synthesized from the elements in sealed tantalum ampoules in an induction furnace. Phase purity of the samples was checked by powder X-ray diffraction. The structures of two members of the solid solution were refined from single crystal X-ray diffractometer data: ZrNiAl type, P � 62m, a = 756.16( 6), c = 413.06(4) pm, wR2 = 0.0402, 328 F 2 values, 16 variables for Gd 0.80(2) Y 0.20(2) AuMg and a = 754.82(7), c = 411.24(4) pm, wR2 = 0.0292, 325 F 2 values, 16 variables for Gd 0.37(1) Y 0.63(1) AuMg. Temperature dependent magnetic susceptibility studies show a continuous decrease of the Néel temperature from T N = 81.1(1) K (GdAuMg) to 3.5(1) K (Gd 0.1 Y 0.9 AuMg). With increasing x in Gd 1-x Y x AuMg the saturation magnetization increases, with a maximal value of 6.44(1) μ B Gd atom À 1 for Gd 0.1 Y 0.9 AuMg at 3 K. The dilution of the gadolinium substructure with yttrium pushes the magnetization isotherms close to Brillouin type behavior (free Gd 3 + ).