Formula omitted] NMR study of Gd–Ni intermetallic compounds

Abstract

The spin-echo NMR technique was used to study the magnetic properties of the following intermetallic compounds of the Gd–Ni series: Gd 2Ni 17, GdNi 5, GdNi 3, GdNi 2 and GdNi, with 155 Gd and 157 Gd nuclei as local probes. These compounds have different crystal structures and order ferri- or ferromagnetically. The NMR measurements were performed at 4.2 and 1.5 K. The NMR spectra were compared to computed line positions obtained from the diagonalization of the complete hyperfine Hamiltonian. The RKKY contribution to the hyperfine field was computed for Gd 2Ni 17 and GdNi 3, and differences in the values of B hf at the two sites of Gd, of the order, respectively, of 18 and 6 T, were thus justified. An intense quadrupole interaction was observed at the Gd sites in the compounds GdNi 5, Gd 2Ni 17, and in one of the sites of the compound GdNi 3; in all these cases, the values of V zz are of the order of 10 22 V/m 2. The NMR results in GdNi are consistent with a direction of magnetization along the b-axis for this compound. The present study presents the first systematics of hyperfine interactions in Gd–Ni compounds.