TY  - THES
AU  - Zimmermann, Bernd
TI  - $\textit{Ab initio}$ description of transverse transport due to impurity scattering in transition-metals
VL  - 89
PB  - RWTH Aachen
VL  - Dr.
CY  - Jülich
M1  - FZJ-2014-05437
SN  - 978-3-89336-985-0
T2  - Schriften des Forschungszentrums Jülich. Reihe Schlüsseltechnologien / Key Technologies
SP  - 164 S.
PY  - 2014
N1  - RWTH Aachen, Diss., 2010
AB  - This thesis attempts to shed light on various spin-orbit driven transport phenomenain materials, as a crucial for the further development of the field of spintronics. Inparticular, 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 $\textit{ab initio}$ 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 5$\textit{d}$ and 6$\textit{sp}$ 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 emergenceof large spin-ip 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 3$\textit{d}$ 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 $\textit{L}$1$_{0}$-ordered alloy FePt and address different kinds of disorder. We showcase the power of our method by treating the very complicated compounds Fe$_{x}$Mn$_{1-x}$Si and MnSi$_{1-x}$Ge$_{x}$, based on the non-Fermi liquid manganese silicide (MnSi). Finally, we also calculate the pure spin Hall effect for 4$\textit{d}$/5$\textit{sp}$ and 5$\textit{d}$/6$\textit{sp}$ impurities in fcc Ir and hcp Re hosts. For the latter, we discover a strong dependence on the electron's spin-polarization direction.
KW  - Dissertation (GND)
LB  - PUB:(DE-HGF)11
UR  - https://juser.fz-juelich.de/record/171881
ER  -