Magnetic hyperfine field at highly diluted Ce impurities in the antiferromagnetic compound GdRh2Si2 studied by perturbed gamma–gamma angular correlation spectroscopy

The magnetic properties of GdRh2Si2 compound were investigated by hyperfine interactions and magnetization measurements. The temperature dependence of the magnetic hyperfine field (mhf) at highly diluted 140La–140Ce probe nuclei in the GdRh2Si2 compound was measured using perturbed gamma–gamma angular correlation spectroscopy. A well-defined magnetic interaction is observed at 140Ce substituting Gd atoms in the compound below the Néel temperature (TN). However, the temperature dependence of mhf shows a deviation from the expected Brillouin-like behavior and a sharp increase of mhf values is observed for temperatures below approximately half of TN. This behavior has been associated with an additional magnetic interaction which is ascribed to the polarization of Ce spin moment induced by the magnetic field coming from Gd ions. A model based on the molecular-field theory is used to fit the temperature dependence of the mhf. The mhf contributions from the probe atom itself and from the magnetic Gd ions of the host matrix are determined. The results are compared to previous measurements of mhf at 140Ce in Gd and GdAg compound. The contribution from the host to the mhf is discussed in terms of the f–s and f–d interactions.

► Unusual temperature dependence of magnetic hyperfine field at Ce replacing Gd atoms. ► Rh and Si contribute decisively to the magnetic exchange between Gd atoms. ► Conduction electron density plays an important role in host–impurity exchange interaction.