[f(k)] FW: Tomorrow: Päivi Törmä: Flat band superconductivity, in the physics colloquium

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Fysiikan kollokvio huomenna!Antero VoutilainenFyysikkokerho, pj
-------- Alkuperäinen viesti --------Lähettäjä: Tero Tapio Heikkilä <tero.t.heikkila at jyu.fi> Päivämäärä: 26.10.2023  12.34  (GMT+02:00) Saaja: jyflstaff at korppi.jyu.fi, "Heinosaari, Teiko" <teiko.heinosaari at jyu.fi>, Antero Voutilainen <puheenjohtaja at jyfk.fi> Aihe: Tomorrow: Päivi Törmä: Flat band superconductivity, in the physics colloquium 
    Welcome to the University of Jyväskylä physics colloquium. 
    
       On Friday 27th October at 10 am in FYS1 and Zoom (passcode 890524):
      Päivi Törmä (Aalto University):
      Flat-band superconductivity
      We have found that superconductivity and
        superfluidity have a connection to quantum geometry [1,2].
        Namely, the superfluid weight in a multiband system has a
        previously unnoticed component which we call the geometric
        contribution. It is proportional to the minimal quantum metric
        of the band. Quantum metric is connected to the Berry curvature,
        and this allows us to relate superconductivity with the
        topological properties of the band. Using this theory, we have
        shown that superconductivity is possible also in a flat band
        where individual electrons would not move. We and other groups
        have shown [3,4] that these results may be essential in
        explaining the observation of superconductivity in twisted
        bilayer graphene and may eventually help realize superconductors
        at elevated temperatures, all the way up to room temperature. In
        addition to the promise of high critical temperatures and strong
        correlation effects, also the quantum transport in flat band
        shows unique behavior [5]: while supercurrent can flow,
        quasiparticle transport is highly suppressed even in
        non-equilibrium conditions. This may have important consequences
        for superconducting devices.
        
        [1] S. Peotta, P. Törmä, Nature Commun. 6, 8944 (2015); A.
        Julku, S. Peotta, T.I. Vanhala, D.-H. Kim, P. Törmä, Phys. Rev.
        Lett. 117, 045303 (2016); P. Törmä, L. Liang, S. Peotta, Phys.
        Rev. B 98, 220511(R) (2018).
        [2] K.-E. Huhtinen, J. Herzog-Arbeitman, A. Chew, B.A. Bernevig,
        P. Törmä, Phys. Rev. B 106 , 014518 (2022); J. Herzog-Arbeitman,
        A. Chew, K.-E. Huhtinen, P. Törmä, B.A. Bernevig,
        arXiv:2209.00007 (2022).
        [3] A. Julku, T.J. Peltonen, L. Liang, T.T. Heikkilä, P. Törmä,
        Phys. Rev. B 101, 060505(R) (2020); X. Hu, T. Hyart, D.I.
        Pikulin, E. Rossi, Phys. Rev. Lett. 123, 237002 (2019); F. Xie,
        Z. Song, B. Lian, B.A. Bernevig, Phys. Rev. Lett. 124, 167002
        (2020).
        [4] P. Törmä, S. Peotta, B.A. Bernevig, Nat. Rev. Phys. 4, 528
        (2022).
        [5] V.A.J. Pyykkönen, S. Peotta, P. Törmä, Phys. Rev. Lett. 130,
        216003 (2023).
      Welcome!
       Coffee will be served in the lobby. Although on-site
        attendance is the preferred option, you can also join via Zoom.
        Please do not send chat messages in Zoom during the talk, except
        if you need to tell about a muted speaker. 
      
      Confirmed colloquium talks in the Fall 2023 (you are welcome to
        suggest more - there are still open slots):
        3.11. Mathias Kläui (Mainz): Antiferromagnetic Spintronics:
          Spintronics without magnetic fields
        10.11. Andreas Norman (UEF): Quantum complementarities in
          vectorial light fields
        17.11. Thomas Cocolios (KU Leuven): Novel radionuclides
          for medical applications: from the nuclear lab to patients
      Tero & Iain
      
      -- 
Tero Heikkilä
Professor, Department of Physics
University of Jyväskylä
    
  

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