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Theory of spin-dependent transport in magnetic solids
Wagenknecht, David ; Turek, Ilja (advisor) ; Minár, Ján (referee) ; Šipr, Ondřej (referee)
of doctoral thesis Theory of spin-dependent transport in magnetic solids David Wagenknecht Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University 2019 Theoretical and ab initio description of realistic material behavior is complicated and combinations of various scattering mechanisms or temperature effects are often neglected, although experimental samples contain impurities and modern electronics work at finite temperatures. In order to remove these knowledge gaps, the alloy analogy model is worked out in this thesis and implemented within the fully relativistic tight- binding linear-muffin-tin orbital method with the coherent potential approximation. This first-principles framework is shown to be robust and computationally efficient and, consequently, employed to investigate bulk solids and their spintronic applications. Unified effect of phonons, magnons, and alloying gives agreement with literature for temperature-dependent electrical transport (longitudinal and anomalous Hall resistivities) and scattering mechanisms are explained from electronic structures. Moreover, novel data help to identify defects in real samples and experimentally hardly accessible quantities are presented, such as spin polarization of electrical current. Calculated results for both zero...
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Theory of spin-dependent transport in magnetic solids
Wagenknecht, David ; Turek, Ilja (advisor) ; Minár, Ján (referee) ; Šipr, Ondřej (referee)
of doctoral thesis Theory of spin-dependent transport in magnetic solids David Wagenknecht Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University 2019 Theoretical and ab initio description of realistic material behavior is complicated and combinations of various scattering mechanisms or temperature effects are often neglected, although experimental samples contain impurities and modern electronics work at finite temperatures. In order to remove these knowledge gaps, the alloy analogy model is worked out in this thesis and implemented within the fully relativistic tight- binding linear-muffin-tin orbital method with the coherent potential approximation. This first-principles framework is shown to be robust and computationally efficient and, consequently, employed to investigate bulk solids and their spintronic applications. Unified effect of phonons, magnons, and alloying gives agreement with literature for temperature-dependent electrical transport (longitudinal and anomalous Hall resistivities) and scattering mechanisms are explained from electronic structures. Moreover, novel data help to identify defects in real samples and experimentally hardly accessible quantities are presented, such as spin polarization of electrical current. Calculated results for both zero...
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Relativistic Theory of Electron Transport in Magnetic Layers
Sýkora, Rudolf ; Turek, Ilja (advisor) ; Šob, Mojmír (referee) ; Drchal, Václav (referee)
Title: Relativistic Theory of Electron Transport in Magnetic Layers Author: Rudolf Sýkora Department / Institute: Institude of Theoretical Physics Supervisor of the doctoral thesis: doc. RNDr. Ilja Turek, DrSc., Department of Condensed Matter Physics Abstract: We review the density-functional theory (DFT) in detail using the Levy Lieb ap- proach. The Kohn Sham scheme is discussed, starting from the simplest spinless non- relativistic case, then including spin and considering potential spin magnetism, and finally deriv- ing the full Kohn Sham Dirac relativistic scheme. The Linear Muffin-Tin Orbital (LMTO) method for electronic-structure calculation is presented, together with mentioning the necessary changes to include the spin-orbit (SO) interaction effects to an otherwise scalar-relativistic (SR) theory. Derivation of an electronic-conductance formula for a layered system is given, based on the Landauer scattering picture and using simple non-equilibrium Green functions. The formal- ism is applied to layered metallic systems of light elements Co, Ni, Cu elements, and to layered systems with a tunnelling barrier, Fe/MgO/Ag and Fe/GaAs/Ag. The effects of the SO interac- tion on the Giant Magnetoresistance (GMR) ratio and/or the Tunnelling Anisotropy Magnetore- sistance (TAMR) for these systems are discussed....
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