Conference Presentation (Invited)

FZJ-2026-01360

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Superconductive Coupling and Josephson Diode Effect in Multi-Terminal Hybrid Structures based on Topological Insulators

Schäpers, T. (Corresponding author)FZJ*

2025

Abstract: Combining s-type superconductors with three-dimensional topological insulators creates a promising platform for fault-tolerant topological quantum circuits based on Majorana braiding. The braiding mechanism is built around a three-terminal Josephson junction. However, implementing this concept requires a deeper understanding of the underlying mechanisms in topological insulator nanoribbon networks equipped with superconducting electrodes. Our devices are fabricated using a combination of selective-area growth of the topological insulator and shadow mask evaporation of the superconductor. Firstly, we investigate nanoribbon kinks and T-junctions of the topological insulator. In kink structures we observed a π-periodic change in conductance depending on the direction of an in-plane magnetic field. We attribute this phenomenon to an orbital effect that leads to the alignment or misalignment of phase-coherent states on the lower and upper surfaces of the kink branches, depending on the orientation of the magnetic field. Next, we measure the transport properties of three-terminal topological insulator-based Josephson junctions and analyze the junctions' cross-coupling. When an out-of-plane magnetic field is applied, a multi-terminal geometry-induced diode effect is observed. Work done in collaboration with: Gerrit Behner, Abdur Rehman Jalil, Kristof Moors, Michael Schleenvoigt, Erik Zimmermann, Alina Rupp, Justus Teller, Franz Fischer, Peter Schüffelgen, Makoto Kohda, Hans Lüth, Detlev Grützmacher.

Keyword(s): Information and Communication (1st) ; Condensed Matter Physics (2nd)

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Contributing Institute(s):

1. Halbleiter-Nanoelektronik (PGI-9)

Research Program(s):

1. 5222 - Exploratory Qubits (POF4-522) (POF4-522)
2. EXC 2004:  Matter and Light for Quantum Computing (ML4Q) (390534769) (390534769)
3. DFG project G:(GEPRIS)491798118 - Magnetische topologische Isolatoren für robuste Majorana Zustände (491798118) (491798118)

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