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In the context of “flat superconductors”, the Berezinskii-Kosterlitz-Thouless (BKT) theory is naturally involved in the discussion, even if only indirectly. BKT physics is in fact necessary to allow for the (quasi-)long-range-order, otherwise prohibited by Mermin-Wagner theorem. However, in 2d superconductors the observation of BKT hallmarks is not so straightforward, because of screening currents, finite size effects and inhomogeneities [1,2,3].
Strong inhomogeneities and correlated disorder might in fact completely mask the BKT transition and the superconducting condensate may show a substantially different phenomenology governed by inhomogeneities themselves [3,4,5].
In this talk, I will discuss the “practical” problems of observing BKT signatures in 2d superconductors.
Starting from a previous Flat Club seminar [6], I will start by reviewing briefly the BKT transtion, addressing some questions previously raised, hopefully triggering new discussions.
You can download the slides for the presentation here (PDF).

[1] L. Benfatto, C. Castellani, T. Giamarchi, In: 40 Years of BKT Theory edited by Jorge V. José (World
Scientific, 2013), Phys. Rev. B 80, 214506 (2009) and Phys. Rev. B 80 214506 (2009)
[2] Pratap Raychaudhuri and Surajit Dutta, J. Phys.: Condens. Matter 34 (2022) 083001
[3] G. Venditti et al Phys. Rev. B 100 6 064506 (2019)
[4] G. Venditti et al SciPost Phys. 15, 239 (2023)
[5] G. Venditti et al SciPost Phys. 15, 230 (2023)

Please register at the doodle if you want to join for pizza!

Location: Stuckelberg, Ecole de Physique
Time: Friday 15 March 2024, 12:10 for pizza, 12:30 start discussion