Superconductivity Achieved in Nanowires Via 5.5m/mT Domain Wall Modulation

Why It Matters

Magnetically tunable superconductivity offers a lithography‑free method to position superconducting segments, enabling reconfigurable quantum logic and topological qubit architectures. This control could dramatically lower power consumption and increase flexibility in superconducting circuits.

Key Takeaways

• Superconductivity appears only in multi‑domain EuS state.
• Domain wall moves 5.5 µm per mT of field.
• Sub‑mT fields reconfigure magnetic texture precisely.
• Enables movable superconducting regions for quantum devices.
• Supports domain‑wall and multi‑domain averaged superconductivity.

Pulse Analysis

The interplay between ferromagnetism and superconductivity has long been a frontier of condensed‑matter research, and the recent demonstration in InAs/EuS/Al nanowires pushes the boundary further. By epitaxially coating an indium‑arsenide core with a europium‑sulphide ferromagnet and an aluminium superconductor, the team created a one‑dimensional platform where the magnetic texture can be tuned in situ. Scanning SQUID magnetometry revealed that a multi‑domain EuS configuration, rather than a saturated single‑domain state, is a prerequisite for the emergence of superconductivity in the aluminium shell.

The experiments showed that a well‑defined magnetic domain wall can be displaced at roughly 5.5 µm per millitesla using magnetic fields well below one millitesla. This level of control is achieved without any lithographic patterning, simply by adjusting the external field and exploiting the low coercivity of EuS. Simultaneous four‑probe differential resistance measurements confirmed that the superconducting phase follows the domain wall, offering a movable, low‑dissipation weak link. Such precision opens a practical route to engineer superconducting diodes, racetrack‑memory readout, and reconfigurable Josephson junctions directly on a nanowire.

From a quantum‑technology perspective, the ability to position superconductivity on demand could accelerate the development of topological qubits and Andreev‑spin qubits, where localized Zeeman fields must be balanced against Cooper‑pair coherence. Magnetically reconfigurable superconductivity also suggests new architectures for superconducting logic and memory that combine fast switching with minimal power loss. Future work will need to distinguish between domain‑wall‑localized and multi‑domain‑averaged superconductivity, refine domain‑wall velocity, and integrate these nanowires into larger circuits, but the present results already signal a versatile toolbox for next‑generation quantum devices.