Abstract:Doping Ni80Fe20 by heavy rare earth atoms alters the magnetic relaxation properties of this material drastically. We show that this effect can be well explained by the slow relaxing impurity mechanism. This process is a consequence of the anisotropy of the on site exchange interaction between the 4f magnetic moments and the conduction band. As expected from this model the magnitude of the damping effect scales with the anisotropy of the exchange interaction and increases by an order of magnitude at low tempera… Show more
“…Another possible reason of the enhanced damping is that the Pt would act as a dopant into the FeNi films. It is consistent with previous studies 22,23 where heavy-metal dopants in FeNi can increase the damping.…”
“…Another possible reason of the enhanced damping is that the Pt would act as a dopant into the FeNi films. It is consistent with previous studies 22,23 where heavy-metal dopants in FeNi can increase the damping.…”
“…This allows us to study with moderate effort the influence of varying the alloy composition on the damping parameter α. Corresponding work has been done in particular using permalloy as a starting material and adding transition metals (TM) [16] or rare earth metals [17]. Fig.…”
A Kubo-Greenwood-like equation for the Gilbert damping parameter α is presented that is based on the linear response formalism. Its implementation using the fully relativistic Korringa-KohnRostoker (KKR) band structure method in combination with Coherent Potential Approximation (CPA) alloy theory allows it to be applied to a wide range of situations. This is demonstrated with results obtained for the bcc alloy system FexCo1−x as well as for a series of alloys of permalloy with 5d transition metals. To account for the thermal displacements of atoms as a scattering mechanism, an alloy-analogy model is introduced. The corresponding calculations for Ni correctly describe the rapid change of α when small amounts of substitutional Cu are introduced.
“…The damping coefficient can be modified by introducing doping elements including rare earths [4][5][6][7] or transition metal 8,9 elements, with the dopant introduced by co-deposition, usually co-sputtering. A disadvantage of this approach is that the entire material is doped.…”
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