Magnetic field at sup(140)Ce in Dy sites in DyX (X=Cu, Ag) compounds studied by perturbed angular correlation spectroscopy

Abstract

The magnetic hyperfine field (mhf) at Dy sites in DyAg and DyCu was investigated with perturbed gamma–gamma angular correlation technique using 140La–140Ce probe nuclei. The temperature dependence of the observed mhf shows a deviation from an expected Brillouin-like behavior with a sharp increase of mhf values for temperatures below approximately half of TN for each compound. This additional magnetic interaction is believed to result from the polarization of Ce spin moments induced by the magnetic field from Dy atoms. The experimental results for the temperature dependence of mhf are fitted by using a model based in the molecular field theory. The results are discussed in terms of the RKKY model for the indirect magnetic coupling between the magnetic Dy ions. r 2008 Elsevier B.V. All rights reserved.