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

Abstract

Perturbed gammaYgamma angular correlation technique was used to measure the magnetic hyperfine field at Gd sites in the intermetallic compound GdAg using the 140 LaY 140 Ce nuclear probe. A major and well-defined magnetic interaction is observed at 140 Ce 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.

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

“…The observed unusual temperature dependence of B hf measured at 140 Ce in GdRh 2 Si 2 is quite similar to that already seen in Gd [8] and GdAg [13]. In Fig.…”

“…Using a model based on molecular field theory [11] with some modifications [12], we have calculated the two contributions to the mhf: from the probe ions themselves and that from the magnetic Gd ions of the host matrix. The results are compared to those obtained from the fit to the temperature dependence of mhf at diluted 140 Ce probes in pure Gd with T C = 293 K [8] and GdAg with T N = 132 K [13] reported previously. These results along with the results from magnetization measurements were used to investigate the coupling between the 4f spins of Gd ions in terms of f-s and f-d interactions.…”

“…(b) Magnetic hyperfine field at Gd sites occupied by 140 Ce probe in Gd, GdAg, and GdRh2Si2 as a function of the reduced temperature T/T0, where T0 is the ordering temperature. Gd orders ferromagnetically at T0 = TC = 292.2 K[8], and GdAg orders antiferromagnetically at T0 = TN = 132 K[13].…”

Magnetic vacancies in antiferromagnetic RAg compounds—A PAC study

“…In such a structure, all 4f-induced contributions to the magnetic hyperfine field at site X are expected to cancel. A finite magnetic hyperfine interaction arises only on the R site, as recently shown for the probe nucleus 140 Ce on the Gd site of GdAg [9].…”

Investigação das interações hiperfinas nos compostos ternários RMn2Si2 e RMn2Ge2 (R = La, Nd, Pr) pela espectroscopia de correlação angular γ - γ perturbada

“…Esse campo de troca é dimensionado para a magnetização reduzida do Fe, por um parâmetro, o qual propõe que a intensidade da interação de troca "host"-impureza é diferente da interação "hosthost". Alguma modificação ao modelo proposto por Jaccarino tem sido adicionadas para levar em conta a contribuição ao B hf dos elétrons de condução, de forma a usar esse modelo com impurezas de terra rara e "host" [5,7,8,9].…”