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Visar resultat 1 - 5 av 149 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Ultrafast Magnetization Dynamics : Element-selective studies of magnetic alloys using ultra short XUV pulses

   Författare :Rameez Saeed Malik; Olof Karis; Uwe Bovensiepen; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; magnetization dynamics; magnetic alloys; HHG; ultrashort laser pulses; magneto-optical Kerr effect MOKE ; Gilbert damping; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : In this thesis, I investigate the ultrafast magnetization dynamics in 3d ferromagnets and their alloys with ultrashort laser pulses. The high harmonics generation (HHG) setup provides extreme-ultraviolet photons with energies 35-72 eV, which is the energy range where 3d metals have their M2,3 absorption edges. LÄS MER

3. 2. Superdiffusive Spin Transport and Ultrafast Magnetization Dynamics : Femtosecond spin transport as the route to ultrafast spintronics

   Författare :Marco Battiato; Olle Eriksson; Hardy Gross; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ultrafast magnetisation dynamics; anomalous diffusion; femtosecond dynamics; magnetism; Materialvetenskap; Materials Science;

   Sammanfattning : The debate over the origin of the ultrafast demagnetization has been intensively active for the past 16 years. Several microscopic mechanisms have been proposed but none has managed so far to provide direct and incontrovertible evidences of their validity. LÄS MER

4. 3. Structured Light for Ultrafast Videography

   Författare :Vassily Kornienko; Förbränningsfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Structured Light; FRAME; Coherence Lifetime Imaging; Optical Diagnostics; Ultrafast Videography; Strukturerad Belysning; FRAME; Koherent Livstidsavbildning; Optisk diagnostik; Ultrasnabb videografi;

   Sammanfattning : Monitoring natural events at ultrafast timescales is a prerequisite for our continued understanding of physical, chemical and biological processes. Due to exponential advancements in knowledge and optical technology, the field of ultrafast videography has seen a sudden uptick in activity beginning in the mid-2010s. LÄS MER

5. 4. The Fate of Electronically Excited States : Ultrafast Electron and Energy Transfer in Solvated Donor-Acceptor Systems

   Författare :Staffan Wallin; Leif Hammarström; Jan Davidsson; Eric Vauthey; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physical chemistry; Electron transfer; Energy transfer; Anisotropy; Porphyrin; Ruthenium tris-bipyridine; Superexchange; Supramolecular; Donor-Acceptor; Charge transfer state; S2 state; Ultrafast; Fysikalisk kemi; Physical chemistry; Fysikalisk kemi;

   Sammanfattning : Processes where a molecule absorbs visible light and then disposes of the excess energy via electron/energy transfer reactions have an important role both in nature (e.g. in photosynthesis) and in many technical applications (e.g. LÄS MER

7. 5. Ultrafast spin dynamics at the nanoscale : using coherent X-ray and terahertz radiation

   Författare :Nanna Zhou Hagström; Stefano Bonetti; Stefan Eisebitt; Ferran Macià Bros; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; XFEL; small-angle X-ray scattering; X-ray holography; ultrafast magnetism; symmetry-breaking; magnetic domains; terahertz; magnetic field enhancement; metamaterial; time-resolved magneto-optical microscope; Physics; fysik;

   Sammanfattning : The field of ultrafast magnetism is driven by the growing need for faster and more efficient magnetic data storage, which comprises the vast majority of the digital information worldwide. However, after more than two decades of intense research, the understanding of the fundamental physical processes governing the transfer of angular momentum necessary for magnetic switching, is still lacking, partially hampered by the appropriate experimental tools. LÄS MER