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AM: Magnetismus
AM 14: Dünne Schichten II
AM 14.8: Talk
Thursday, March 29, 2001, 16:45–17:00, S 5.2
Magnetism of ultrathin Ho films and tuning of exchange coupling in Ho/Y superlattices with deuterium — •Vincent Leiner, Danielle Labergerie, and Hartmut Zabel — Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum
Ho/Y superlattices have been studied extensively in the past concerning their phase transition and the propagation of the magnetic spiral through the Y spacer layer, mediated by the RKKY interaction. Hydrogen in Y has been used for optical switching between the metallic reflecting YH2 and a transparent YH3 phase, signalling a metal-insulator transition. We have investigated the deuterium uptake and magnetism of a [Ho(77Å)/Y(52Å)]× 30 superlattice. Neutron reflectivity measurements at RT confirm that D preferentially occupies the Y spacer layers. We have taken LT reciprocal space maps of the Ho/Y superlattice before and after exposure to deuterium. Before deuterium exposure, the magnetic satellite peak τ is visible, convoluted with the satellite peaks of the chemical period. After deuterium exposure the splitting of the magnetic τ peak vanishes. This strongly indicates that the magnetic correlation among the Ho layers is lifted and that the Ho layers scatter independently as isolated magnetic films. Thus deuterium in the Y eliminates the possibility for RKKY exchange coupling because of a depletion of the Y density of states at the Fermi surface. – Supported by BMBF 03-ZA4BC1