Current-phase relation of a WTe2 Josephson junction

Abstract

When a topological insulator is incorporated into a Josephson junction, the system is predicted to reveal the fractional Josephson effect with a 4$\pi$-periodic current-phase relation. Here, we report the measurement of a $4\pi$-periodic switching current through an asymmetric SQUID, formed by the higher-order topological insulator WTe${}_2$. Contrary to the established opinion, we show that a high asymmetry in critical current and negligible loop inductance are not sufficient by themselves to reliably measure the current-phase relation. Instead, we find that our measurement is heavily influenced by additional inductances originating from the self-formed PdTe${}_{\text{x}}$ inside the junction. We therefore develop a method to numerically recover the current-phase relation of the system and find the $1.5\mu \text{m}$ long junction to be best described in the short ballistic limit. Our results highlight the complexity of subtle inductance effects that can give rise to misleading topological signatures in transport measurements.

As accepted by Nano Letters, includes main text (7 pages, 3 figures) and supplementary information (16 pages, 7 figures)

References in corpus (4)

• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Topological Insulators with Inversion Symmetry
• Fermion-parity anomaly of the critical supercurrent in the quantum spin-Hall effect
• Current-phase relation of a WTe2 Josephson junction

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• Current-phase relation of a WTe2 Josephson junction
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• Limitations of the current-phase relation measurements by an asymmetric dc-SQUID
• Direct measurement of a $\sin (2\phi )$ current phase relation in a graphene superconducting quantum interference device
• Driving a Josephson Traveling Wave Parametric Amplifier into chaos: effects of a non-sinusoidal current-phase relation
• SQUID oscillations in PbTe nanowire networks
• Crystalline superconductor-semiconductor Josephson junctions for compact superconducting qubits
• Supercurrent reversal in Zeeman-split Josephson junctions
• Unveiling Topological Hinge States in the Higher-Order Topological Insulator WTe${}_2$ Based on the Fractional Josephson Effect
• Pre-Patterned Superconducting Contacts for Clean Superconductor-Topological Material Interfaces Enabling Long-Range Josephson Coupling
• Probing the topological protection of edge states in multilayer tungsten ditelluride with the superconducting proximity effect
• Gate- and flux-tunable sin(2$\phi$) Josephson element with proximitized Ge-based junctions