The crystal structure and magnetic properties of the rare-earth nickel (RNi) compounds

Abstract

The spin-echo NMR technique was used to study the magnetic properties of the following intermetallic compounds of the Gd–Ni series: Gd2Ni17, GdNi5, GdNi3, GdNi2 and GdNi, with 155Gd and 157Gd 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 Gd2Ni17 and GdNi3, and differences in the values of Bhf 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 GdNi5, Gd2Ni17, and in one of the sites of the compound GdNi3; in all these cases, the values of Vzz are of the order of 1022 V/m2. 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.