Physikalisches Kolloquium der Sektion Physik im Wintersemester 2020 / 2021

Termin: dienstags 16.15 (Videokonferenz).

Verantwortlich: Prof. Michael Bonitz

 

  • 03.11.2020: frei

  • 10.11.2020: Prof. Fabio Caruso (ITAP, CAU Kiel)

    ** Antritts-Vorlesung **

    Electronic-structure theory of two-dimensional quantum materials:
    from fundamental interactions to novel emergent phenomena
     

    A detailed understanding of the quantum-mechanical interactions between the constituents of matter holds the promise of driving the discovery of new functional materials and designing their properties. First-principles electronic-structure theory has evolved into a robust framework to address this challenge, as it allows to establish the inherent relationship between the macroscopic properties of solids and elementary interactions at the nano scale.
    In the Computational Solid-State Theory group, we develop and employ state-of-the-art first-principles approaches for the theoretical description of the electronic and vibrational properties of two-dimensional materials, such as graphene and transition-metal dichalcogenides. These compounds are characterized by a unique interplay of charge confinement, reduced dielectric screening, and strong light-matter coupling. This makes them prone to exhibit a rich spectrum of emergent phenomena, including charge-density waves, polarons, and circular dichroism. Through a few examples taken from our recent research activities, I will illustrate the predictive power achievable by means of modern first-principles techniques based on many-body perturbation theory in the description of these phenomena. I will further discuss how these activities relate and contribute to the open challenges in the field of electronic structure theory.

 

  • 17.11.2020: Prof. Philipp Werner (Uni Fribourg, CH)

    Titel:
    Abstract:


    Einladender: Prof. Caruso

  • 24.11.2020: Prof. Bradley J. Siwick (McGill University Montreal)

    Structure and Dynamics with Ultrafast Electron Microscopes: Moving Beyond the Molecular Movie

    Bradley J. Siwick

    In this talk I will describe how combining ultrafast lasers and electron microscopes in novel ways makes it possible to directly ‘watch’ the time-evolving structure of condensed matter on the fastest timescales open to atomic motion.  By combining such measurements with complementary (and more conventional) spectroscopic probes one can develop structure-property relationships for materials under even very far from equilibrium conditions and explore how light can be used to control the properties of materials.

    I will give several examples of the remarkable new kinds of information that can be gleaned from such studies and describe how these opportunities emerge from the unique capabilities of the current generation of ultrafast electron microscopy instruments.  For example, in diffraction mode it is possible to identify and separate lattice structural changes from valence charge density redistribution in materials on the ultrafast timescale and to identify novel photoinduced phases that have no equilibrium analogs.   It is also possible to directly probe the strength of the coupling between electrons and phonons in materials across the entire Brillouin zone and to probe nonequilibrium phonon dynamics (or relaxation) in exquisite detail.  

    I will assume no familiarity with ultrafast lasers or electron microscopes.

    [1] Morrison et al Science 346 (2014) 445
    [2] Otto et al, PNAS, 116 (2019) 450
    [3] Stern et al, Phys. Rev. B 97 (2018) 165416
    [4] Rene de Cotret et al, Phys. Rev. B 100 (2019) 214115

    Einladender: Prof. Bauer
     

  • 01.12.2020: frei

  • 08.12.2020: Prof. Ido Kaminer (Technion Israel)

    Einladender: Prof. Talebi
     

  • 15.12.2020: Prof. Dr. David Go (University of Notre Dame)

    Titel: Plasma Catalysis
    Abstract:

    Einladender: Prof. Benedikt

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