Ab initio description of transverse transport due to impurity scattering in transition-metals

Auteurs

• Bernd Zimmermann

Paramètres

• Manuels
• Manuels universitaires

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This thesis explores spin-orbit driven transport phenomena in materials, essential for advancing spintronics. It focuses on the skew-scattering mechanism in dilute alloys, which leads to the anomalous and spin Hall effects, as well as spin-relaxation processes. The research develops tools for accessing these phenomena through ab initio calculations using the full-potential all-electron Korringa-Kohn-Rostoker Green-function method. Key innovations include a new tetrahedron method for calculating complex, multi-sheeted Fermi surfaces in transition-metal compounds and a highly scalable computer program for precise scattering property calculations. The tetrahedron method is first applied to calculate the Elliott-Yafet spin-mixing parameter on the Fermi surfaces of 5d and 6sp metals, revealing an unexplored dependence on the electron's spin-polarization direction. This anisotropy can reach significant values in uniaxial hcp crystals due to large spin-flip hot areas on the Fermi surface, influenced by the crystal's low symmetry. A model demonstrates the interplay between the orbital character of states in the Brillouin zone and matrix elements of the spin-flip part of the spin-orbit coupling operator. Additionally, the thesis presents the first calculation of the skew-scattering contribution to the anomalous Hall effect (AHE) in dilute alloys with a ferromagnetic host, identifying trends across the periodic table. A strong correla

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• Année de publication: 2014