Sökning: "Flat bands"

Visar resultat 1 - 5 av 13 avhandlingar innehållade orden Flat bands.

  1. 1. Robust Platforms for Superconductivity : Disorder Robustness and Topological Density of States Peaks

    Författare :Tomas Löthman; Annica M. Black-Schaffer; Carsten Honerkamp; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Superconductivity; Odd-Frequency Superconductivity; Nematic superconductivity; Topological Phases of Matter; Flat bands; Van Hove Singularity; Graphene; Twisted Bilayer Graphene; Rhombohedral graphite; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : We explore the connection between robust material platforms for superconductivity and the modern condensed matter physics paradigms of two-dimensional materials, topological states of matter, and odd-frequency superconductivity. Specifically, the recent discoveries of gapless topological matter and truly two-dimensional materials with graphene have greatly expanded the class of materials for which topology produces large, robust, even singular, density of states (DOS) peaks in the electronic structure that in turn are highly susceptible to new ordered states of matter, including superconductivity. LÄS MER

  2. 2. Hg Cuprate Superconductors Technological and Conceptual Tools

    Författare :Rafael Gatt; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; mercury; high pressure; pulsed laser deposition; crystal growth; high temperature superconductors; cluster calculations; flat bands; thin oxide films; powder diffraction; structure refinement; phase transition; electronic structure; liquid phase epitaxy;

    Sammanfattning : This work concerns superconductivity in the cuprates. It touches some of the problems that this field displays. As a representing case, the Hg based cuprates are chosen. LÄS MER

  3. 3. Crystallization of the superconducting phase in unconventional superconductors

    Författare :Patric Holmvall; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; pattern formation; spontaneous symmetry breaking; Andreev bound states; mesoscopic superconductivity; phase crystals; thin superconducting films; phase transitions; non-local Ginzburg-Landau theory; time-reversal symmetry; flat bands; unconventional superconductivity; quasiclassical theory; translational symmetry; cuprates; inhomogeneous superconductivity;

    Sammanfattning : Superconductivity is a macroscopic quantum phenomenon, in the sense that a macroscopic number of electrons form a pair condensate, that occupies a single ground state. The electrons in this state are phase-coherent, breaking global U (1)-symmetry, and spatial variations of the phase imply superflows that usually cost kinetic energy, resulting in a uniform and rigid phase. LÄS MER

  4. 4. 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

  5. 5. Strongly Correlated Moiré Materials

    Författare :Ahmed Abouelkomsan; Emil Bergholtz; Vladimir Juričić; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Theoretical Physics; teoretisk fysik;

    Sammanfattning : Recent advances in materials science have established Moiré materials as a new highly tunable and versatile form of quantum matter. When two dimensional atomic layers are brought into proximity, a tiny relative twist or a slight lattice mismatch produces Moiré patterns manifested in a superlattice structure with a lattice constant that is much larger than the lattice constants of the constituent layers. LÄS MER