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%0 Thesis
%A Zimmermann, Bernd
%T Ab initio description of transverse transport due to impurity scattering in transition metals
%V 89
%C Aachen
%I Publikationsserver der RWTH Aachen University
%M RWTH-CONV-145336
%B Schriften des Forschungszentrums Jülich : Reihe Schlüsseltechnologien
%P 164 S. : Ill., graph. Darst.
%D 2014
%Z Zugl.: Aachen, Techn. Hochsch., Diss., 2014
%X This thesis attempts to shed light on various spin-orbit driven transport phenomena in materials, as a crucial for the further development of the field of spintronics. In particular, we address the skew-scattering mechanism in dilute alloys, which gives rise to the anomalous and spin Hall effect, as well as spin-relaxation processes. We create the tools to access these quantities from ab initio calculations in the framework of the full-potential all-electron Korringa-Kohn-Rostoker Green-function method, by (a) developing and implementing a new tetrahedron method for the calculation of complicated, multi-sheeted Fermi surfaces even of complex transition-metal compounds, and (b) developing an efficiently parallelized and thus highly scalable computer program (up to thousands of processors) for the precise calculation of scattering properties. In a first application of the new tetrahedron method, we calculate the Elliott-Yafet spin-mixing parameter on the Fermi surfaces of 5d and 6sp metals, and discover a yet unexplored dependence on the electron’s spin-polarization direction. As we show, this anisotropy can reach gigantic values in uniaxial hcp crystals due to the emergence of large spin-flip hot-areas or hot-loops on the Fermi surface, supported by the low symmetry of the hcp crystal. A simple model is able to reveal an interesting interplay between the orbital character of the states at special points, lines or areas in the Brillouin zone and the matrix-elements of the spin-flip part of the spin-orbit coupling operator. We further calculate the skew-scattering contribution to the anomalous Hall effect (AHE) in dilute alloys based on a ferromagnetic host for the first time. A systematic study of 3d impurities in bcc Fe, as well as the non-magnetic hosts Pd, Pt and Au, allows us to identify trends across the periodic table. In all our calculations, we also observe a strong correlation between the spin Hall effect and anomalous Hall effect in these materials, which is of interest for the creation and detection of strongly spin-polarized currents. A Fermi-surface analysis of the contributions to the AHE reveals a non-trivial, peaked behavior at small hot-spots around spin-orbit lifted degeneracies. We then proceed to the more complicated L10-ordered alloy FePt and address different kinds of disorder. We showcase the power of our method by treating the very complicated compounds FeMnSi and MnSiGe, based on the non-Fermi liquid manganese silicide (MnSi). Finally, we also calculate the pure spin Hall effect for 4d/5sp and 5d/6sp impurities in fcc Ir and hcp Re hosts. For the latter, we discover a strong dependence on the electron’s spin-polarization direction.
%K Spin-Bahn-Wechselwirkung (SWD)
%K Dichtefunktionalformalismus (SWD)
%K Ab-initio-Rechnung (SWD)
%K Streutheorie (SWD)
%F PUB:(DE-HGF)11 ; PUB:(DE-HGF)3
%9 Dissertation / PhD ThesisBook
%U https://publications.rwth-aachen.de/record/459420