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TT: Fachverband Tiefe Temperaturen

TT 42: Superconductivity: Tunneling and Josephson Junctions

TT 42.7: Vortrag

Donnerstag, 20. März 2025, 11:00–11:15, H32

Gate-Controlled Supercurrents in Three-Terminal Devices Made on Industrial Grade SiO2 and Al2O3 — •Leon Ruf, Jennifer Koch, Elke Scheer, and Angelo Di Bernardo — University of Konstanz, Universitätsstraße 10, 78457 Konstanz

Gate-controlled supercurrent (GCS) is a growing, highly debated field of research. It was found that in gated three-terminal devices made of Ti and Al the supercurrent could be modulated by the application of a gate voltage [1]. The authors attribute their observation to a direct electric field effect, which would pave the way for future CMOS compatible transistors. Contrary, other works reported about a leakage related effect: high-energy quasiparticle emission through vacuum [2], phonon-induced heating of the electronic system [3], out-of-equilibrium state induced by phonons and/or high energy electrons without sizeable heating [4]. Here we are studying the GCS in Nb and NbRe Dayem bridges on industrial grade SiO2 and Al2O3. Our results reveal a strong correlation between the substrate material and the GCS parameters, such as suppression voltage and stability. Herby, SiO2 and Al2O3 show major differences. Further, our results suggest that for both SiO2 and Al2O3 the leakage current is mediated via defects giving rise to trap-assisted tunneling. We discuss our results in the light of the above-mentioned mechanism [1-4].
[1] De Simoni et al., Nat. Nanotechnol. 13, 802 (2018);
[2] Alegria et al., Nat. Nanotechnol. 16, 404 (2021);
[3] Ritter et al., Nat. Electron. 5, 71 (2022);
[4] Basset et al., Phys. Rev. Rese. 3, 043169 (2021).

Keywords: Nanodevices; gate controlled supercurrent; trap-assisted tunneling