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TT: Fachverband Tiefe Temperaturen
TT 18: Superconductivity: Poster
TT 18.28: Poster
Monday, March 18, 2024, 15:00–18:00, Poster C
Current phase relation of HgTe nanowire Josephson junctions in an axial magnetic field — •Niklas Hüttner, Wolfgang Himmler, Ralf Fischer, Dmitriy Kozlov, Dieter Weiss, and Christoph Strunk — Institute for Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
The band structure of Topological surface states hosted by 3D Topological insulators such as HgTe can be tuned to a Dirac shape. For this a magnetic field (B∥) is applied axial to HgTe nanowire structures1. Using such nano wires as weak links in a Josephson junction allows to tune between trivial and topological supercurrents2. We directly probe the current phase relation (CPR) of a such a device with the asymmetric SQUID method. The nanowire junction is in the short junction regime2 and features a strongly anharmonic CPR that can be described by the generalized Kulik-Omelyanchuk theory3. At B∥=0 a high transparency of D≈0.95, an induced gap Δ*≈0.15 meV, and an approximate number of channels n≈9 to 10 is evaluated3. Varying B∥ controls the magnetic flux Φ enclosed by the topological surface state. Even for |Φ|≪Φ0 the ϕ0 shift can be adjusted between ± π. In the range 0−1.5 Φ0 we observe a strong modulation of both the critical current and the content of higher harmonics. — The HgTe material was kindly provided by Nikolay N. Mikhailov and Sergey A. Dvoretsky, Novosibirsk.
[1] A. Cook et al., Phys. Rev. B 84, 201105 (2011)
[2] R. Fischer et al., Phys. Rev. Res. 4, 013087 (2022)
[3] A. A. Golubov et al., Rev. Mod. Phys. 76, 411 (2004)
Keywords: 3D-Topological Insulator; Ballistic Josephson Junctions; HgTe