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Next Quantum Material Seminar :


Thursday May 8, 2pm

Valentin Taufour (UC Davis)

“Combining Topology and Superconductivity: Can we discover unconventional superconductors methodically?”



To access this seminar:

K223, Institut Néel CNRS, Building K, 1st floor, Room Remy Lemaire



Unconventional superconductors have Cooper pairs with lower symmetries than in conventional superconductors. In most unconventional superconductors, the additional symmetry breaking occurs in relation to typical ingredients such as strongly correlated Fermi liquid phases, magnetic fluctuations, or strong spin-orbit coupling in noncentrosymmetric structures. In this presentation, I will show that the time-reversal symmetry breaking in the superconductor LaNiGa2 is enabled by its previously unknown topological electronic band structure, with Dirac lines and a Dirac loop at the Fermi level. Two symmetry related Dirac points even remain degenerate under spin-orbit coupling. These unique topological features enable an unconventional superconducting gap in which time-reversal symmetry can be broken in the absence of other typical ingredients. Our findings provide a route to identify a new type of unconventional superconductors based on nonsymmorphic symmetries and will enable future discoveries of topological crystalline superconductors.

J. R. Badger et al. Communications Physics 5, 22 (2022)
Y. Quan et al. Phys. Rev. B 105,064517 (2022)



Next scheduled seminars are:

  • Thursday 15 June, 2pm: Elena Hassinger (Technische Universität Dresden)
  • Monday 19 June, 2pm: Cristiano Nisoli


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The organizers:

Elsa Lhotel, elsa.lhotel@neel.cnrs.fr
Florence Levy-Bertrand, florence.levy-bertrand@neel.cnrs.fr