Orateur
Description
The question of understanding limits on the superconducting transition temperature Tc is of great fundamental and technological importance. I will begin with a pedagogical introduction to this question and describe recent progress on deriving rigorous upper bounds [1] on the Tc of 2D superconductors applicable to a wide range of quantum materials and to ultracold atomic gases. I will illustrate the usefulness of these bounds by comparing with recent experiments on a variety of systems where standard BCS theory fails. Next, motivated by twisted bilayer graphene, I will generalize our bounds to flat bands with non-trivial topology and obtain rigorous quantum geometric bounds for flat band superconductivity [2]. I will conclude by discussing the open question [3] of obtaining general upper bounds on Tc in 3D.
[1] T. Hazra, N. Verma, M. Randeria, Phys. Rev. X 9, 031049 (2019)
[2] N. Verma, T. Hazra, M. Randeria, Proc. Nat. Acad. Sci. 118, e2106744118 (2021)
[3] M. Randeria in “50 years of RG: In memory of M.E. Fisher”, edited by A. Aharony et al. (World Scientific, 2024); Mod. Phys. Lett. B 38, 2430004 (2024)