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Regensburg 2022 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 20: Topology: Poster Session

TT 20.9: Poster

Wednesday, September 7, 2022, 15:00–18:00, P1

Current phase relation of HgTe nanowire Josephson junctions in an axial magnetic field — •N. Hüttner1, W. Himmler1, D. A. Kozlov2, N. N. Mikhailov2, S. A. Dvoretsky2, D. Weiss1, and C. Strunk11Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany — 2Novosibirsk, Russia

Topological insulators (TIs) such as HgTe nanowires host topological surface states. Their band structure can be tuned to a Dirac shape via the application of an axial magnetic field (B) [1]. For proximitized nanowires this is expected to tune between trivial and topological supercurrents as recent experiments suggest [2]. Here we directly probe the current phase relation (CPR) of a tunable TI Josephson junction. The TI junction consists of a HgTe nanowire proximitized by superconducting Nb contacts embedded into an asymmetric DC-SQUID together with an Al/AlOx/Al junction. Beeing in the short junction regime [2], the TI junction features a strongly anharmonic CPR [3,4] with a high average transparency of D≈0.95 for n≈9±2 channels [4]. Varying B controls the magnetic flux enclosed by the nanowire surface. In the range 0−1.5 Φ0 we observe a strong modulation of the critical current and interference of phase shifted contributions of individual channels creating a great variety of CPR shapes.
 [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).
 [4] C. Baumgartner et al., Phys. Rev. Lett. 126, 037001 (2021).

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