Unveiling the 3D Spin Texture of Nanowires Using Integrated Microscopy Techniques

This study integrates multiple microscopy techniques to investigate the effect of introducing axial compositional gradients on the magnetic properties of Fe-Ni ferromagnetic nanowires. We study the chemical structure of the nanowires using photoemission electron microscopy and transmission (X-ray and electron) microscopy. We explore the magnetic properties through magnetic force microscopy, complemented by micromagnetic simulations, and we characterize the 3D magnetization vector by measuring magnetic circular dichroism using X-ray microscopies. We observe that variations in the Fe/Ni ratio induce localized magnetic curling in Fe-rich regions, while Ni-rich segments predominantly exhibit axial magnetization, demonstrating how compositional gradients can control magnetic domain configurations on the nanoscale. Our results highlight the value of multimodal imaging for uncovering the interplay among structural, chemical, and magnetic properties in complex nanostructures. These findings represent a significant step toward the manipulation of magnetic domains in nanowires, which is essential for future devices based on 3D nanomagnetic architectures.