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7 février 2019: 1 événement

séminaire

  • Topological states and fermion zoo in 3D and 2D systems based on HgCdTe and III-V semiconductors

    Jeudi 7 février 11:00-12:00 - Sergey Krishtopenko - Laboratoire Charles Coulomb, Université Montpellier 2

    Topological states and fermion zoo in 3D and 2D systems based on HgCdTe and III-V semiconductors

    Résumé : Fermions in high energy physics are classified as Dirac, Majorana or Weyl particles according to different solutions of Schrödinger equation. However, being free of the stringent Lorentz symmetry, low-energy excitations in condensed matter systems significantly extend the fermion zoo, known from the Standard model.
    In the first part of my talk, I focus on so-called Kane fermions [1], known for zinc-blend crystals. I will show that bulk crystals hosting Kane fermions with negative-rest mass have multiple branches of topological surface states [2], in contrast to conventional topological insulators. Then, I briefly present our experimental results on temperature-driven topological phase transition and observation of massless Dirac fermions in HgTe quantum well (QW) [3,4]. Finally, I show that tunnel-coupling between two HgTe QWs yields very reach phase diagram of the system [5].
    In the second part of my talk I will present multi-layer 2D system based on III-V semiconductors, which offers a flexible platform for realization of high-temperature Quantum Spin Hall Insulator (QSHI), massless Dirac fermions and analog of bilayer graphene analog [6]. The first experimental results from our group will be shown as well [7,8]. If I have enough time at the end of the talk, I will briefly discuss possibility of realization of stable 2D Weyl fermions and the 2nd order QSHI on the basis of this conventional 2D system.
    [1] F. Teppe, M. Marcinkiewicz, S.S. Krishtopenko et al., Nat. Commun 7, 12576 (2016).
    [2] S. S. Krishtopenko, M. Antezza, F. Teppe (to be published).
    [3] S. S. Krishtopenko et al. Phys. Rev. B 94, 245402 (2016).
    [4] A. M. Kadykov, S. S. Krishtopenko, B. Jouault et al., Phys. Rev. Lett. 120, 086401 (2018).
    [5] S. S. Krishtopenko, W. Knap, F. Teppe. Sci. Reports 6, 30755 (2016).
    [6] S. S. Krishtopenko, F. Teppe, Science Advances 4, eaap7529 (2018).
    [7] S. S. Krishtopenko et al. Phys. Rev. B 97, 245419 (2018).
    [8] S. S. Krishtopenko et al. (to be published).

    Lieu : LPS, bât 510, Moyen Amphi

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