Electronic Transport in Materials

Transport properties within the Boltzmann transport equation for metallic multi-layer structures as well as bulk materials, were the prime topic of this work. Ab initio total energy calculations for Hydrogen loaded metallic multi-layers were performed in order to shed some light onto problem of H depleted layers at the interfaces that have been experimentally observed. It was explained in connection with structural relaxation of the interface layers.Further on conductivity behavior of Fe/V vs. Mo/V during Hydrogen load was discussed. The difference in, on first sight, rather similar multi-layer structures was explained by the magnitude of Hydrogen induced Vanadium expansion. Problem of variation of conductivity with changed c/a ratio of metals and semiconductors in general was addressed as well. The variations due to change of the Fermi surface of the corresponding materials were observed as well as some intriguing general patterns. The phenomenon could be regarded as piezoresistivity on electronic structure level. For the 3d transition metals variation of conductivity/resistivity through the period was studied.A possible explanation for anomalous behavior of Manganese resistivity due to its much greater lattice constant in comparison to its neighbors in the period is presented. Field of disordered alloys and low dimensional magnetism…
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2 Introduction
3 Theoretical Models
3.1 Free Electron Model
3.2 Band Structure
3.2.1 Tight Binding Approximation
3.2.2 The LMTO Method
3.2.3 The PAW Method
3.3 DFT
3.3.1 Hartree Fock, Xα, and Thomas-Fermi methods
3.3.2 Density as the basic variable
3.3.3 Kohn-Sham Density Functional Theory
3.3.4 Approximate Exchange-Correlation Functionals
3.4 CPA
4 Electronic Transport
4.1 Boltzmann Approach
4.1.1 Relaxation Time Approximation
4.1.2 Non-equilibrium Distribution Function
4.1.3 Simplifications
4.1.4 Electric Conductivity
4.1.5 Vertex Corrections
4.2 Kubo-Greenwood Formalism
4.2.1 Fluctuation-Dissipation
4.2.2 Vertex Corrections
4.3 Landauer-Büttiker Transport
4.3.1 Landauer Formul
4.3.2 Buttiker Generalization
4.3.3 Conductance Fluctuations
5 Results
5.1 Hydrogen dissolution in metals
5.2 Electronic conductivity in materials

Author: Meded, Velimir

Source: Uppsala University Library

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