Temperature Dependence of the Magnetic Hyperfine Field at 140Ce on Gd Sites in GdAg Compound

Perturbed gamma-gamma angular correlation technique was used to measure the magnetic hyperfine field at Gd sites in the intermetallic compound GdAg using the 140La→140Ce nuclear probe. A major and well-defined magnetic interaction is observed at 140Ce substituting Gd sites in GdAg below 130 K, corresponding to a ferromagnetic ordering of Gd moments. The temperature dependence of magnetic hyperfine field, however, shows a sharp deviation from an expected Brillouin-like behavior for temperatures below 75 K. This additional magnetic interaction is believed to result from the polarization of Ce spin moments induced by the magnetic field from Gd atoms.