Nuclear magnetic resonance studies of ferromagnetic hydrides based on rare earth-cobalt intermetallics: The effect of hydrogen on spectra of the hyperfine field at 59Co nuclei in GdCo 5H x and YCo 5H x

Abstract

In an attempt to extend the application of the nuclear magnetic resonance (NMR) technique to ferromagnetic hydrides, we carried out the first survey of NMR in GdCo 5H x and YCo 5H x . Spectra of the hyperfine field at 59Co nuclei were measured by the spin echo method for various hydrogen concentrations. The hydrogen has a considerably greater effect on the Co II signal from the cobalt nuclei in the cobalt-only layers of the RCo 5 (R  Gd, Y) structure than on the Co I signal from the cobalt nuclei in the layers consisting of rare earth and cobalt atoms: the intensity of the Co II signal decreases and becomes broader as the amount of absorbed hydrogen increases. This result is explained by assuming that in GdCo 5 and YCo 5 hydrogen atoms are preferentially located in the cobalt-only layers and that they distribute the quadrupole interaction and/or cause the inhomogeneous hyperfine field at Co II.