Sökning: "Olof Karis"

Visar resultat 6 - 10 av 11 avhandlingar innehållade orden Olof Karis.

1. 6. New Materials for Spintronics : Electronic structure and magnetism

   Författare :Ronny Knut; Olof Karis; Biplab Sanyal; Hermann Durr; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Spintronics; X-ray photoemission; XPS; XMCD; XAS; magnetic semiconductors; HIKE; HAXPES; multilayer; monte carlo; magnetism; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : Materials exhibiting new functionalities due to interdependent electric (e.g. conductivity) and magnetic properties are potentially interesting for spintronics applications. LÄS MER

3. 7. 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

4. 8. An X-ray Spectroscopic Study of Perovskites Oxides and Halides for Emerging Devices

   Författare :Dibya Phuyal; Olof Karis; Manuel Bibes; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; perovskite oxides; halide perovskites; x-ray spectroscopy; electronic structure; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : This thesis investigates the electronic structures on several perovskite oxide and halide materials with a focus on light harvesting applications. The systematic study of the electronic properties of the transition metal oxides and post-transition metal halides is a key point if one is to understand their properties. LÄS MER

5. 9. Effect of Substrate on Bottom-Up Fabrication and Electronic Properties of Graphene Nanoribbons

   Författare :Konstantin Simonov; Olof Karis; Nils Mårtensson; Alexei Preobrajenski; Alessandro Baraldi; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; graphene nanoribbons; bottom-up; substrate; metal contact; electronic structure; electron doping; PES; ARPES; NEXAFS; STM; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : Taking into account the technological demand for the controlled preparation of atomically precise graphene nanoribbons (GNRs) with well-defined properties, the present thesis is focused on the investigation of the role of the underlying metal substrate in the process of building GNRs using bottom-up strategy and on the changes in the electronic structure of GNRs induced by the GNR-metal interaction. The combination of surface sensitive synchrotron-radiation-based spectroscopic techniques and scanning tunneling microscopy with in situ sample preparation allowed to trace evolution of the structural and electronic properties of the investigated systems. LÄS MER

7. 10. 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