Regensburg 2025 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 29: Poster II

HL 29.82: Poster

Dienstag, 18. März 2025, 18:00–20:00, P1

Side-contacted narrow superconducting finger on quantum anomalous Hall insulator — •Bibek Bhujel, Anjana Uday, Gertjan Lippertz, Alexey A. Taskin, and Yoichi Ando — Physics Institute II, University of Cologne, Zülpicher Str. 77, 50937 Köln, Germany

Recently, the evidence for superconducting pair correlation is obtained in the chiral edge states of a vanadium-doped (Bi_xSb_1−x)₂Te₃ thin film, tuned to the quantum anomalous Hall insulator phase by observing the negative nonlocal resistance downstream from a narrow superconducting (grounded) Nb finger electrode fabricated on the top [1]. This negative downstream resistance is due to the crossed Andreev reflection (CAR) process, which creates superconducting correlations in the chiral edge. To investigate this observation further, we are currently fabricating side-contacted Al and Nb finger electrodes on the etched QAHI. One of the main advantages of fabricating the side-contacted electrodes is their low contact resistance, which has high reproducibility. We will report on our progress on this project so far.

[1] Uday, A., Lippertz, G., Moors, K. et al. Induced superconducting correlations in a quantum anomalous Hall insulator. Nat. Phys. 20, 1589*1595 (2024). https://doi.org/10.1038/s41567-024-02574-1

Keywords: Superconducting proximity effect; Quantum anomalous Hall insulator; Chiral edge state; Side-contacted electrodes; Superconducting correlation