Speaker
Description
Three-dimensional (3D) magnetic nanostructures provide a versatile platform for exploring magnetization processes governed by geometry and topology beyond planar systems [1-3]. In particular, spiral nanowires represent a typical system in which curvature and local structural variations can strongly influence magnetic domain wall nucleation and dynamics [4-5].
In this work, we investigate FEBID-fabricated 3D spiral nanowires using shadow X-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM). By applying in-plane magnetic fields with different orientations and sequences, we systematically control the nucleation and evolution of magnetic domains in the spirals. Due to the geometrical constraints of the spiral structure, domain walls nucleate at well-defined locations where the local wire orientation becomes perpendicular to the applied magnetic field. By changing the field direction, the nucleation position along the spiral can therefore be tuned. In addition, the local slope of the 3D structure modifies the effective cross-section during thin-film deposition, leading to spatial variations in film thickness. Such geometrically induced thickness gradients modulate local magnetic parameters, including effective anisotropy and domain wall energy. As a result, the 3D geometry defines a complex magnetic energy landscape that governs the evolution of domain walls under applied magnetic fields.
The measurements reveal a range of geometry-driven behaviors, including domain wall automotion, local pinning, and interactions between domain walls. These results highlight the potential of engineered 3D magnetic nanostructures as platforms for controlling domain wall dynamics and for developing functional 3D spintronic architectures.
[1] Nat. Commun. 8, 1 (2017).
[2] APL Mater. 8, 010701 (2020).
[3] J. Phys.: Condens. Matter 37, 143502 (2025).
[4] Sci. Rep. 3, 1492 (2013).
[5] ACS Nano 16, 8860 (2022).