Sökning: "Electron-phonon coupling"

Visar resultat 1 - 5 av 14 avhandlingar innehållade orden Electron-phonon coupling.

  1. 1. Quantum Materials Probed by Light and Electron Spectroscopy

    Författare :Karin von Arx; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; RIXS; superconductivity; electron- phonon coupling; quantum materials; spin-orbit coupling; ARPES;

    Sammanfattning : As new technologies rely heavily on materials’ properties, the quest for novel tunable electronic and magnetic materials occupies a large part of nowadays research efforts. Most promising materials are quantum materials, which exhibit a wide range of exotic electronic and magnetic phenomena and often show a great sensitivity to external perturbations such as temperature, pressure or chemical doping. LÄS MER

  3. 2. Ultrafast spin dynamics and relaxation in metallic ferromagnets

    Författare :Vivek Unikandanunni; Stefano Bonetti; Olof Karis; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Magnetization dynamics; Three temperature model; Cobalt; Anisotropy; Electron-phonon coupling; THz; Platinum; Silver; fysik; Physics;

    Sammanfattning : We performed ultrafast demagnetization measurements on epitaxial hcp-cobalt thin film with the easy axis in the plane of the film by pumping the sample with 400 nm radiation and probing the magneto-optic effects in the longitudinal magneto optic Kerr effect geometry using 800 nm radiation. The in-plane magnetic anisotropy of the sample enabled us to measure the demagnetization dynamics along two different crystalline directions, namely along the easy axis and at 45 degrees between the easy and hard axes. LÄS MER

  4. 3. Ultrafast spin, lattice, and electron dynamics in thin metallic films : in the terahertz, near-infrared, and extreme ultraviolet regimes

    Författare :Vivek Unikandanunni; Stefano Bonetti; Andreas Rydh; Jurgen Lindner; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Terahertz; near-infrared; extreme ultraviolet; epitaxial cobalt; transient grating; field emission; gold; platinum; electron-phonon coupling; magneto-crystalline anisotropy; nanoscale dynamics; ultrafast spin dynamics; magnetic inertia; nutation; pump-probe; two-temperature model; Fowler-Nordheim tunneling; fysik; Physics;

    Sammanfattning : In this thesis, we studied the ultrafast spin and electron dynamics triggered by electromagnetic radiation belonging to three different regions of the electromagnetic spectrum, namely terahertz, near-infrared and extreme ultraviolet. By performing pump–probe measurements, we explored the role of the lattice in ultrafast spin and electron dynamics in metallic thin films. LÄS MER

  5. 4. A Theoretical Study of Charge Transport in Molecular Crystals

    Författare :Elham Mozafari; Sven Stafström; Magnus Johansson; Linköpings universitet; []
    Nyckelord :Molecular Crystals; Charge transport; Polaron; Holstein model; Peierls coupling;

    Sammanfattning : The main objective of this thesis is to provide a deeper understanding of the charge transport phenomena occuring in molecular crystals. The focus is on the stability and the dynamics of the polaron as the charge carrier.To achieve this goal, a series of numerical calculations are performed using the semi-emprical "Holstien-Peierls" model. LÄS MER

  7. 5. Theoretical studies of the coupling between electronic, vibrational, configurational and structural effects in metal borides

    Författare :Erik Johansson; Björn Alling; Johanna Rosén; Paul Erhart; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : This thesis addresses theoretical studies of the coupling between electronic, vibrational, configurational and structural degrees of freedom in metal borides. The effect of external conditions of temperature, pressure and composition on the interplay between internal degrees of freedom is investigated. LÄS MER