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Visar resultat 1 - 5 av 277 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Phase transitions in novel superfluids and systems with correlated disorder

   Författare :Hannes Meier; Mats Wallin; Asle Sudbø; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; condensed matter physics; phase transitions; critical phenomena; spin models; quantum phase transitions; quantum fluids; superfluidity; superconductivity; disordered systems; Bose glass; dirty bosons; vortex pinning; statistical mechanics; Monte Carlo simulation; Wolff algorithm; classical worm algorithm; Wang-Landau algorithm; Fysik; Physics;

   Sammanfattning : Condensed matter systems undergoing phase transitions rarely allow exact solutions. The presence of disorder renders the situation  even worse but collective Monte Carlo methods and parallel algorithms allow numerical descriptions. LÄS MER

3. 2. Phase transitions in high-temperature superconductors

   Författare :Jack Lidmar; KTH; []
   Nyckelord :Superconductivity; Vortices; Phase transitions; Strongly correlated fermions; High-temperature superconductivity; Monte Carlo simulations.; TECHNOLOGY; TEKNIKVETENSKAP;

   Sammanfattning : Thermal fluctuations and disorder strongly influence the behaviour of hightemperature superconductors. In particular the vortices play a key role in determining their properties. In this thesis the main focus lies on phase transitions, both in ultra-thin films and in three-dimensional systems, which are driven by vortex fluctuations. LÄS MER

4. 3. First-Principles Studies of Materials Properties : Pressure-Induced Phase Transitions & Functional Materials

   Författare :Thanayut Kaewmaraya; Rajeev Ahuja; Scheicher Ralph; Naurang Saini; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Density functional theory; Pressure-induced phase transitions; Ab-initio molecular dynamic; hybrid functional; Ab-initio random structure searching; Phase change material; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : This thesis presents the first-principles studies of materials properties within the framework of the density functional theory (DFT). The thesis constitutes three main parts, i. e., pressure-induced phase transitions in solids, data-storage and clean-energy materials. LÄS MER

5. 4. Computer Simulations of Simple Liquids with Tetrahedral Local Order : the Supercooled Liquid, Solids and Phase Transitions

   Författare :Måns Elenius; Mikhail Dzugutov; Jonathan Doye; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Simple liquids; glasses; liquid-glass transition; supercooled liquids; tetrahedral liquids; phase transitions; quasicrystals; molecular dynamics; Condensed matter physics; Kondenserade materiens fysik; Liquid physics; Vätskefysik; numerisk analys; Numerical Analysis;

   Sammanfattning : The understanding of complex condensed matter systems is an area of intense study. In this thesis, some properties of simple liquids with strong preference for tetrahedral local ordering are explored. These liquids are amenable to supercooling, and give complex crystalline structures on eventual crystallisation. LÄS MER

7. 5. Phase Transitions and Phase Formation of Hydrogen in Quasi-2D Lattices

   Författare :Stefan Olsson; Björgvin Hjörvarsson; Yuh Fukai; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; hydrogen; finite-size effects; long-ranged interactions; superlattices; phase transitions; elastic interaction; Fysik; Physics; Fysik;

   Sammanfattning : The role of the dimensionality and strain state of metallic lattices on the phase behavior of dissolved hydrogen was explored. Metallic superlattices with well defined hydrogen absorption potential on the nm scale, were utilized as test systems. LÄS MER