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Visar resultat 6 - 10 av 25 avhandlingar som matchar ovanstående sökkriterier.

1. 6. Interaction and disorder in helical conductors

   Författare :Anders Ström; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; physics; helical conductors; topological insulators; Anderson localization; condensed matter;

   Sammanfattning : Different effects from electron-electron interactions and disorder in helical and quasi-helical conductors are studied using bosonisation and renormalisation group methods. The combined effects of Rashba spin-orbit interaction and magnetic Kondo-type impurities in the helical edge liquids of quantum spin Hall insulators, are investigated. LÄS MER

3. 7. Evaluation of NMR Knight shifts in metallic nanoparticles and topological matter

   Författare :Wassilios Papawassiliou; Andrew Pell; Niklas Hedin; Ulla Gro Nielsen; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; solid-state NMR; Knight shifts; metallic systems; topological matter; nanoparticles; DFT calculations; Physical Chemistry; fysikalisk kemi;

   Sammanfattning : Elucidating the surface electron states of transition metal compounds is of primary importance in main heterogeneous catalytic processes, such as the hydrogen and oxygen evolution reactions.  Key property in all these processes is the position of the energy of the d-band center relative to the Fermi-level of the catalyst; it must be shifted close to the Fermi level to achieve balance between adsorption and desorption of the catalyst and the adsorbate. LÄS MER

4. 8. Symmetry-protected topological phases: From Floquet theory to machine learning

   Författare :Oleksandr Balabanov; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Topological quantum matter; neural networks; Floquet theory;

   Sammanfattning : It is by now a well known fact that boundary states in conventional time-independent topological insulators are protected against perturbations that preserve relevant symmetries. In the first part of this thesis, accompanying Papers A - C, we study how this robustness extends to time-periodic (Floquet) topological insulators. LÄS MER

5. 9. Geometry, Topology and Emergence in Moiré Systems

   Författare :Ahmed Abouelkomsan; Emil Johansson Bergholtz; Felix von Oppen; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Moiré materials; Topological phases; Fractional Chern insulators; Quantum geometry; Quantum Hall effects; Theoretical Physics; teoretisk fysik;

   Sammanfattning : The experimental discovery of correlated insulators and superconductivity in highly tunable Van der Waals heterostructures, such as twisted bilayer graphene, has highlighted the role of moiré patterns, resulting from tiny relative twists or lattice constant mismatches, in realizing strongly correlated physics. A key ingredient is the existence of very narrow flat bands where interaction effects are dominant. LÄS MER

7. 10. Magnetic solotronics near the surface of a semiconductor and a topological insulator

   Författare :Mohammad Reza Mahani; C.M. Canali; Biplab Sanyal; Linnéuniversitetet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Magnetic solotronics; Transition metal dopants; Dilute magnetism in semiconductors and topological insulators; Atomistic tight-binding models; DFT; Spin dynamics; Magnetic anisotropy; Scanning tunneling microscope.; Condensed Matter Physics; Kondenserade materians fysik;

   Sammanfattning : Technology where a solitary dopant acts as the active component of an opto-electronic device is an emerging  field known as solotronics, and bears the promise to revolutionize the way in which information is stored, processed and transmitted. Magnetic doped semiconductors and in particular (Ga, Mn)As, the archetype of dilute magnetic semiconductors, and topological insulators (TIs), a new phase of quantum matter with unconventional characteristics, are two classes of quantum materials that have the potential to advance spin-electronics technology. LÄS MER