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Visar resultat 1 - 5 av 11 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Electronic Structure and Statistical Methods Applied to Nanomagnetism, Diluted Magnetic Semiconductors and Spintronics

    Författare :Lars Bergqvist; Olle Eriksson; Warren Pickett; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Materials science; spintronics; magnetism; Monte Carlo; critical temperature; exchange interactions; percolation; disorder; noncollinear; electronic structure; Materialvetenskap; Materials science; Teknisk materialvetenskap;

    Sammanfattning : This thesis is divided in three parts. In the first part, a study of materials aimed for spintronics applications is presented. More specifically, calculations of the critical temperature in diluted magnetic semiconductors (DMS) and half-metallic ferromagnets are presented using a combination of electronic structure and statistical methods. LÄS MER

  3. 2. Scaling and Gating Attosecond Pulse Generation

    Författare :Christoph Heyl; Atomfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Coherent imaging; Ultrafast electron dynamics; Single attosecond pulses; Attosecond pulse trains; XUV sources; High-order harmonic generation; XUV frequency combs; Fysicumarkivet A:2014:Heyl;

    Sammanfattning : High-order harmonic generation (HHG) provides the basis for attosecond light sources delivering coherent pulses in the extreme ultraviolet spectral region. Such light sources are employed for a variety of applications within imaging, attosecond spectroscopy, and high-precision frequency metrology. LÄS MER

  4. 3. Generation of Ultrashort Pulses – From Femtoseconds to Attoseconds

    Författare :Maite Louisy; Atomfysik; []
    Nyckelord :Attosecond; Femtosecond; Ultrashort laser pulses; Ultrafast optics; High-order harmonic generation; extreme ultraviolet; Post-compression; Hollow-core capillary; d-scan; Optical gating; Fysicumarkivet A:2017:Louisy;

    Sammanfattning : Electronic dynamics takes place on the attosecond timescale and can thus only be studied using a tool with attosecond temporal resolution. High harmonic generation (HHG) provides coherent attosecond pulses in the extreme ultraviolet spectral region. LÄS MER

  5. 4. Hydrogen in ultrathin vanadium layers

    Författare :Gabriella Andersson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Fysik; Physics; Fysik; Fysik; Physics;

    Sammanfattning : The influence of elastic boundary conditions on the thermodynamics of hydrogen in vanadium were investigated using resistometry, x-ray diffraction and nuclear reaction analysis. To provide varying lattice strain states Mo/V (110) and Fe/V (001) superlattices with thickness L of individual layers in the range 3-16 monolayers (ML) were used. LÄS MER

  7. 5. Strong Correlation Effects in Bosonic and Fermionic Systems Through an Unbiased Quantum Monte Carlo Approach

    Författare :Emil Blomquist; Egor Babaev; Johan Carlström; Barbara Capogrosso Sansone; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fysik; Physics; Teoretisk fysik; Theoretical Physics;

    Sammanfattning : Strongly interacting many-body quantum systems constitute some of the most challenging problems in physics, and exact analytical solutions are rare. In this thesis, we will investigate the models of two such systems numerically using the unbiased worm-algorithm Monte Carlo method. LÄS MER