Magnetic texture modulated superconductivity in superconductor/ferromagnet shells of semiconductor nanowires

TL;DR

This study demonstrates that magnetic textures in superconductor/ferromagnet nanowires can modulate superconductivity, with superconductivity appearing only in multi-domain states and being controllable by small magnetic field changes.

Contribution

The paper provides experimental evidence that magnetic textures in superconductor/ferromagnet shells can control superconductivity, introducing a new way to manipulate superconducting regions in nanowires.

Findings

Superconductivity occurs only in multi-domain states of EuS in InAs/EuS/Al nanowires.

Magnetic textures are position-dependent and reconfigurable by small magnetic fields.

Localized superconducting regions can be moved by magnetic domain wall manipulation.

Abstract

In a one-dimensional ferromagnet-superconductor nanowire, magnetism can suppress superconductivity except where the Zeeman field is suppressed, for example domain wall superconductivity (DWS) near magnetic domain walls or multi-domain-averaged superconductivity (MDAS) in multi-domain states where the net magnetization over the coherence length averages to nearly zero. Here we study full-shell InAs/EuS/Al nanowires using scanning SQUID magnetometry and transport, and find superconductivity in the Al shell only when the EuS is in a multi-domain state, consistent with both DWS and MDAS, and absent in the saturated single-domain state. Scanning SQUID magnetometry further shows that the EuS magnetic texture is position dependent and reconfigurable by small changes in external magnetic field, including moving a well-defined domain wall at $\approx$5.5 $\mu$m/mT with sub-mT fields, implying that any associated localized superconducting region would likewise be movable. Such magnetic texture controlled superconductivity along a nanowire may be useful for topological qubits, Andreev spin qubits, superconducting logic, and memory devices.