Ferromagnetic nanotubes belong with the field of 3D nanomagnetism, which is gaining attention due to the discovery of new topologies and curvature-induced phenomena. Our research primarily addresses cylindrical nanotubes, which represent an interesting interplay between curvature effects and core-shell interfaces conducive to spintronic applications. Our focus lies in examining the azimuthal curling of magnetisation, a result of curvature-induced magneto-elastic anisotropy, leading to a low stray field for applications and non-reciprocal spin wave propagation from an academic standpoint. We have used CoNiB nanotubes via electroless plating in ion-track-etched polycarbonate templates, with dimensions ranging from 160 to 500 nm in diameter, 20 to 80 nm in wall thickness, and span several tens of micrometres in length. These were largely investigated with Transmission Electron Microscopy (TEM), to extract structural and magnetic information. The application of smaller fields (2-10 mT) triggered DW transformations, motion, and partial magnetisation rotation along the nanotube axis. The nature and width of the domain walls were experimentally determined and cross-verified using micromagnetic modelling translated into phase images. This investigation provides the foundational groundwork for future studies on DW dynamics and spin-wave propagation. It also contributes to the conceptual development of racetrack memories that would operate by shifting magnetic domain walls in nanotubes

Plus d'information :https://www.spintec.fr/phd-defense-magnetic-imaging-of-domain-wall-structure-and-dynamics-in-nanotubes/​
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