sd-type Exchange Interactions in Nonhomogeneous Ferromagnets

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dc.creatorHitchon, W. N. G.
dc.creatorParker, G. J.
dc.creatorRebei, A.
dc.date2004-07-07
dc.date.accessioned2026-07-07T02:59:04Z
dc.date.available2026-07-07T02:59:04Z
dc.descriptionMotivated by a need to understand spin-momentum transport in CPP (current perpendicular to the plane) structures, a quantum field theoretical treatment of spin-spin interactions in ferromagnets is presented. The sd interaction of the conduction electrons and the magnetic medium is treated non-perturbatively from first principles in real space. The localized magnetic moments also interact with each other through a Heisenberg exchange potential. To take into account correlation effects, a second quantized formulation is used. The semi-classical limit is taken by using a coherent-state path-integral technique which also allows us to go beyond a linear-response approach. We derive a set of coupled equations of motion for the nonuniform magnetization, the spin current and the two-point correlation functions of the magnetization. The rate of change of the magnetization is shown to obey a generalized Landau-Lifshitz equation that takes into account interaction with the conduction electrons. Within the relaxation time approximation it is shown that the polarization of the conduction electrons obeys a diffusion equation. The diffusion tensor, which has off-diagonal terms due to the sd exchange interaction, is now explicitly dependent on the magnetization of the medium. We also show that the magnetization fluctuations satisfy a diffusion-type equation. The derived equations are used in two illustrative examples.
dc.description41 pages, 15 figs
dc.identifierhttps://arxiv.org/abs/cond-mat/0407150
dc.identifierhttp://arxiv.org/abs/cond-mat/0407150
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/24363
dc.subjectMaterials Science
dc.titlesd-type Exchange Interactions in Nonhomogeneous Ferromagnets
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