Semiconductor - Ferromagnetic Insulator - Superconductor Nanowires: Stray Field and Exchange Field

TL;DR

This paper reports on the growth, structural analysis, and magnetic properties of semiconductor-ferromagnetic insulator-superconductor nanowires, demonstrating their potential for spin-based quantum computing applications.

Contribution

It presents the first hybrid epitaxy of InAs/EuS/Al nanowires with detailed interface analysis and magnetic tuning, advancing materials for quantum technologies.

Findings

Epitaxial growth of InAs/EuS/Al nanowires achieved with complex interface matching.

Magnetic anisotropy allows easy tuning into single magnetic domains.

Evidence of a hard induced superconducting gap and magnetic exchange fields.

Abstract

Nanowires can serve as flexible substrates for hybrid epitaxial growth on selected facets, allowing for design of heterostructures with complex material combinations and geometries. In this work we report on hybrid epitaxy of semiconductor - ferromagnetic insulator - superconductor (InAs/EuS/Al) nanowire heterostructures. We study the crystal growth and complex epitaxial matching of wurtzite InAs / rock-salt EuS interfaces as well as rock-salt EuS / face-centered cubic Al interfaces. Because of the magnetic anisotropy originating from the nanowire shape, the magnetic structure of the EuS phase are easily tuned into single magnetic domains. This effect efficiently ejects the stray field lines along the nanowires. With tunnel spectroscopy measurements of the density of states, we show the material has a hard induced superconducting gap, and magnetic hysteretic evolution which indicates that the magnetic exchange fields are not negligible. These hybrid nanowires fulfil key material requirements for serving as a platform for spin-based quantum applications, such as scalable topological quantum computing.