Conference Presentation (Invited)

FZJ-2026-01358

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Superconductive coupling and diode effect in topological insulator-based multi-terminal Josephson junctions

Schäpers, T. (Corresponding author)FZJ*

2025

Abstract: The combination of s-type superconductors with three-dimensional topological insulators creates a promising platform for fault-tolerant topological quantum circuits based on Majorana braiding. The backbone of the braiding mechanism is a three-terminal Josephson junction. Implementing this concept requires a deeper understanding of the underlying mechanisms in topological insulator nanoribbon networks equipped with superconducting electrodes. The samples for our experiments are fabricated by a combination of selective-area growth of the topological insulator and shadow mask evaporation of the superconductor. As a first step, we investigate nanoribbon kinks and T-junctions of the topological insulator. In kink structures, a π-periodic change of the conductance is observed as a function of the angle of an in-plane magnetic field. We attribute this phenomenon to an orbital effect leading to an alignment or misalignment of the phase-coherent states on the lower and upper surfaces of the kink branches depending on the magnetic field orientation. The experimental results are supported by a theoretical analysis based on a surface Rashba-Dirac model and tight-binding simulations. As a next step, the transport properties of topological insulator-based three-terminal Josephson junctions are measured and the cross-coupling of the junctions is analyzed. Under the application of an out-of-plane magnetic field, a multi-terminal geometry induced diode effect is observed.Work done in collaboration with: Gerrit Behner, Abdur Rehman Jalil, Kristof Moors, Michael Schleenvoigt, Jonas Kölzer, Erik Zimmermann, Daniel Rosenbach, Alina Rupp, Gregor Mussler, Peter Schüffelgen, 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. DFG project G:(GEPRIS)390534769 - EXC 2004: Materie und Licht für Quanteninformation (ML4Q) (390534769) (390534769)
3. DFG project G:(GEPRIS)491798118 - Magnetische topologische Isolatoren für robuste Majorana Zustände (491798118) (491798118)

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