Seminars

26 Jan 2022
  • Elio Koenig (MPI Stuttgart)

    26 Jan 2022  4:00 pm - 5:00 pm
    https://zoom.us/j/276783458

    Topological (non-)linear transport and optics.

    In this talk, I will give an overview of the theory of anomalous transport and optics in the linear, and particularly in the non-linear regime. I focus on the non-linear Hall, gyrotropic Hall, and circular photogalvanic effects in systems with prominent Berry curvature. I will explicitly discuss the role of impurities, including skew scattering and side jump effects, as well as newly discovered diffractive effects, and will sketch a rigorous derivation of this theory from Keldysh quantum field theory. Both in the linear anomalous Hall effect and in its non-linear or optical counterparts, impurity contributions can be of equal order as intrinsic effects or may even dominate the response. I will also demonstrate that in the diffusive limit, Fick's theory is supplemented by an additional current. Materials applications of the presented theory range from Weyl semimetals and van-der-Waals heterostructures to unconventional superconductors.

    The speaker will be happy to stay for discussions after the seminar.

    [1] L Powalla, J Kiemle, EJ König, et al.; arXiv:2106.15509,
    [2] EJ König, A Levchenko, Annals of Physics; 168492 (2021),
    [3] EJ König, M Dzero, A Levchenko, DA Pesin; PRB 99, 155404 (2019),
    [4] EJ König, HY Xie, DA Pesin, A Levchenko, PRB 96, 075123 (2017),
    [5] EJ König, A Levchenko, PRL, 118 (2), 027001 (2017).

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2 Feb 2022
  • Oliver Dowinton (Manchester)

    2 Feb 2022  4:00 pm - 5:00 pm
    https://zoom.us/j/276783458

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9 Feb 2022
  • Adrian Ceferino (NGI)

    9 Feb 2022  4:00 pm - 5:00 pm
    https://zoom.us/j/276783458

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16 Feb 2022
  • Stephen Power (Dublin)

    16 Feb 2022  4:00 pm - 5:00 pm
    https://zoom.us/j/276783458

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