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Visar resultat 1 - 5 av 32 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Calculation of magnetism and its crystal structure dependence

   Författare :Peter James; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Fysik; Physics; Fysik; fysik; Physics;

   Sammanfattning : The subject of the present thesis is a theoretical investigation of magnetism and its crystal structure dependence by means of electronic-structure calculations from first principles. The theoretical treatment is based on density functional theory and the so called linear muffin-tin orbital method is used in its full-potential version as well as in an atomic sphere approximation. LÄS MER

3. 2. Magnetism and Structure in Metallic Multilayers

   Författare :Erik Holmström; Turek Ilja; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Magnetism; Interfaces; Structure; KKR-ASA; CPA; Quantum Well; Fysik; Physics; Fysik;

   Sammanfattning : The interplay between magnetism and structure has been studied in magnetic multilayers by electronic structure calculations based on density functional theory and analyzed in terms of models. The main ideas behind the Korringa-Kohn-Rostocker Green’s function method are described and the implementation of the coherent potential approximation is outlined. LÄS MER

4. 3. First-principles Studies of Local Structure Effects in Magnetic Materials

   Författare :Marcio Costa; Anders Bergman; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; magnetic anisotropy; DMFT; magnetism; DFT; Materialvetenskap; Materials Science;

   Sammanfattning : This thesis focus on the magnetic behavior, from single atoms to bulk materials. The materials considered in this thesis have been studied by computational methods based on ab initio theory, density functional theory (DFT), including treatment of the spin-orbit coupling, non-collinear magnetism, and methods capable of treating discorded systems. LÄS MER

5. 4. Transport phenomena in quantum wells and wires in presence of disorder and interactions

   Författare :Valeria Vettchinkina; Matematisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; time-dependent density-functional theory; disorder; electron correlation; Lowdimensional semiconducting systems; transport phenomena; Fysicumarkivet F:2012:Vettchinkina;

   Sammanfattning : Present-day electronics employ circuits of smaller and smaller dimensions, and today the length scales are so small that the laws of physics which rule micro-cosmos, quantum mechanics, become directly important. This thesis reports on theoretical work on electron transport in different nanostructures. LÄS MER

7. 5. Development and application of Muffin-Tin Orbital based Green’s function techniques to systems with magnetic and chemical disorder

   Författare :Andreas Kissavos; Igor Abrikosov; Hubert Ebert; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematical physics; Theoretical Physics; Muffin-Tin Orbital method; Calculations; Magnetism; Lloyd’s formula; Mathematical physics; Matematisk fysik;

   Sammanfattning : Accurate electronic structure calculations are becoming more and more important because of the increasing need for information about systems which are hard to perform experiments on. Databases compiled from theoretical results are also being used more than ever for applications, and the reliability of the theoretical methods are of utmost importance. LÄS MER