Sökning: "classical spin models"

Visar resultat 1 - 5 av 16 avhandlingar innehållade orden classical spin models.

  1. 1. Theoretical Studies of Two-Dimensional Magnetism and Chemical Bonding

    Författare :Oleksiy Grechnyev; Olle Eriksson; Alexander Lichtenstein; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; spin Hamiltonians; quantized spin models; Heisenberg model; spin waves; self-consistent spin-wave theory; dipolar interaction; density functional theory; chemical bonding; overlap population; MAX phases; metal hydrides; Fysik; Physics; Fysik;

    Sammanfattning : This thesis is divided into two parts. In the first part we study thermodynamics of the two-dimensional Heisenberg ferromagnet with dipolar interaction. This interaction breaks the conditions of the Mermin-Wagner theorem, resulting in a finite transition temperature. LÄS MER

  3. 2. Criticality and Frustration: Classical and Quantum Spin Models in Two Dimensions

    Författare :Per Fröjdh; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : We investigate two-dimensional spin models and begin with an introduction to critical phenomena with emphasis on classical systems with boundaries and conformal invariance. Then we introduce the antiferromagnetic quantum Heisenberg model with frustrating interactions. LÄS MER

  4. 3. 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

  5. 4. Spectral Methods for Self-Assembly

    Författare :Erik Edlund; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; classical spin models; patterns; isotropic interactions; colloids; Self-assembly;

    Sammanfattning : Conventional manufacturing relies on robotics and chemistry to create, shape and combine components into products. Nature shows us an alternative route: by carefully designing interactions between components, they can be made to spontaneously self-assemble into complex arrangements. LÄS MER

  7. 5. Quantum Kinetic Theory for Plasmas : spin, exchange, and particle dispersive effects

    Författare :Robin Ekman; Gert Brodin; Jens Zamanian; Bengt Eliasson; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; teoretisk fysik; Theoretical Physics;

    Sammanfattning : This thesis is about developing and studying quantum mechanical models of plasmas. Quantum effects can be important at high densities, at low temperatures, and in strong electromagnetic fields, in various laboratory and astrophysical systems. LÄS MER