Nuclear Orientation as a Tool for Investigation of Magnetic Multilayers with Rare Earths

Abstract

Low-temperature nuclear orientation (NO) is presented as a useful tool to study the behaviour of rare earth (RE) ionic magnetic moments in magnetic multilayers. NO is shown to give rather direct information about the direction of RE ionic moments in such low-dimensional systems. In particular, the perpendicular magnetic anisotropy (PMA) can be directly monitored using RE atoms as probes. The potential of NO is demonstrated by our recent results, which concern the Fe/Tb multilayers. We have studied NO of 160 Tb in Fe(40Å)/Tb(xÅ) (x = 5-30) and found that the Tb magnetic moments show PMA at low external magnetic fields (B ext). PMA of the Tb spins is found to be more pronounced when the Tb layer is thinner. It was found that B ext has a complicated influence on the Tb magnetic moment misalignment, which is connected with an interplay between PMA, the exchange interactions and the shape and magnetic crystalline anisotropy.

Low temperature nuclear orientation observations of severe neutron activation damage in ( 160 Tb)TbNiAl 4

“…In particular, rare earth (RE) based amorphous alloys [1] and multi-layer structures have yielded information on preferred directions of the local ionic RE moments under various applied magnetic field strengths, assuming parallelism between electronic magnetic moment, magnetic hyperfine field (MHF), and, in those cases where required, the principal electric field gradient (EFG) [2]. For these latter studies a common approach has been the use of the strongly quadrupolar LTNO probe, 160 Tb, in unannealed samples, post the thermal neutron activation; unannealed, presumably, in part due to the fragility of the samples under study and in part due to the established absence of significant neutron activation damage observed in the extensive Berlin LTNO and NMRON studies on 160 Tb in elemental Tb [3,4].…”