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TT: Fachverband Tiefe Temperaturen

TT 15: Focus Session: Evolution of Topological Materials into Superconducting Nanodevices (joint session HL/TT)

TT 15.8: Talk

Monday, March 18, 2024, 17:00–17:15, EW 202

Proximity induced superconducting gap in Bi-containing thin TI and highly ordered TI films grown on the Nb(110) surface — •Artem Odobesko, Felix Friedrich, Robin Boshuis, and Matthias Bode — Julius-Maximilians-Universität Würzburg,Physikalisches Institut, Experimentelle Physik II, Am Hubland, 97074 Würzburg, Germany

A superconductor (SC) in contact with a non-SC metal leads to a proximity effect, wherein Cooper pairs from the SC infiltrate the metal. The proximity effect has recently regained attention due to its potential for achieving topological superconductivity within heterostructures of 3D topological insulators (TI) combined with conventional s-wave SC. Theoretical predictions suggest the emergence of Majorana zero-energy modes within the vortices of such TI/SC heterostructures. The magnitude of the proximity-induced gap is pivotal for the robustness of Majorana zero modes and in general distinct from proximity pairing correlations. The current experiments are aimed at examining the induced SC-gap on the exposed surface of thin Bi-containing slabs -Bi(111), Bi(110) and Bi₂Te₃ - grown on Nb(110) substrate. The characteristics of the induced SC-gap are not solely dependent on the thickness of the slab; they are also strongly influenced by the matching of Fermi surfaces between the SC and non-SC materials at their interfaces. The band structure correspondence and band bending at the interface, plays a crucial role in generating a robust proximity-induced SC-gap. It underscores the necessity to explore compatible pairs of SC and non-SC materials for effective band matching.

Keywords: Proximity effect; Topological Supercondcutivity; Topological insulators