Deuterium-induced magnetic decoupling in a Ho(00.1)/Y superlattice

Ho/Y superlattices have been studied extensively in the past concerning their phase transition and the propa- gation of the magnetic spiral through the Y spacer layer. Hydrogen in rare-earth metals is known to alter the elec- tronic and magnetic properties. By means of neutron scatter- ing, we have investigated the change of the magnetic spiral and phase transition of a (77 A Ho(00.1)/52 A Y)30 super- lattice upon deuteration. Neutron reflectivity confirms that deuterium preferentially occupies the Y spacer layers, main- taining the structural coherence of the superlattice. Low- temperature reciprocal space maps of the pristine Ho/ Ys u- perlattice exhibit a magnetic satellite peak τ, convoluted with the satellite peaks of the chemical period, indicative for ex- change coupling between the Ho layers mediated by the Y spacers. After deuterium uptake the splitting of the τ peak vanishes. The spiral becomes confined to the individual Ho blocks, similar to single thin Ho films. The ordering tempera- ture, TN, is found to be ≈ 118 K and constant under deuterium loading. Thus coupling-decoupling the Ho blocks does not affect the ordering temperature, whereas it depends on the in- dividual Ho layer thickness via scaling.