Sökning: "disordered systems"

Visar resultat 1 - 5 av 88 avhandlingar innehållade orden disordered systems.

  1. 1. Cluster model of disordered systems : application to doped semiconductors and a simple model polymer

    Författare :Rolf G. Riklund; Linköpings universitet; []
    Nyckelord :;

    Sammanfattning : In this thesis we study with an extended cluster model calculation the combined effect of disorder and electron-electron interaction on the electronic structure of doped semiconductors and a simple model polymer chain. First a one-band model using a Hartree calculation is compared to other authors result for the impurity band using less realistic Hamiltonians. LÄS MER

  3. 2. Theory of Disordered Magnets

    Författare :Oleg E. Peil; Börje Johansson; Hubert Ebert; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; disordered alloys; magnetic alloys; spin glasses; ab initio calculations; Monte Carlo methods; Physics; Fysik;

    Sammanfattning : Studying magnetic properties of disordered alloys is important both for the understanding of phase transformations in alloys and from the point of view of fundamental issues of magnetism in solids. Disorder in a magnetic system can result in unconventional magnetic structures, such as spin glass, which have rather peculiar features. LÄS MER

  4. 3. Superinductance and fluctuating two-level systems: Loss and noise in disordered and non-disordered superconducting quantum devices

    Författare :David Niepce; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Disordered Superconductors; Nanowire; Superinductor; Quantum information; Superconducting circuits; Superinductance; TLS; Two-level Systems;

    Sammanfattning : In this thesis, we first demonstrate that a disordered superconductor with high kinetic inductance can realise a microwave low-loss, non-dissipative circuit element with impedance greater than the quantum resistance. This element, known as a superinductor, can suppress the fluctuations of charge in a quantum circuit. LÄS MER

  5. 4. Collective behavior of disordered magnetic systems

    Författare :Tomas Jonsson; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Materials science; Materialvetenskap; Materials science; Teknisk materialvetenskap; Solid State Physics; fasta tillståndets fysik;

    Sammanfattning : Magnetic properties of disordered and frustrated magnets have been experimentally investigated. The magnetic systems in focus in this work are spin-glasses and frozen ferrofluids (suspensions of nano-sized magnetic particles). LÄS MER

  7. 5. Superfluid Phase Transitions in Disordered Systems

    Författare :Hannes Meier; Mats Wallin Wallin; Peter Olsson; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : This thesis presents results from large scale Monte Carlo simulations of systems subject to a superfluid phase transition in the presence of disorder. The simulations are performed by state-of-the-art, collective Monte Carlo algorithms treating phase degrees of freedom in effective models with amplitude fluctuations integrated out. LÄS MER