We report the imaging of magnetic domains in ferromagnetic CoNiB
nanotubes with very long aspect ratio, fabricated by electroless
plating. While axial magnetization is expected for long tubes made of
soft magnetic materials, we evidence series of azimuthal domains. We
tentatively explain these by the interplay of anisotropic strain and/or
grain size, with magneto-elasticity and/or anisotropic interfacial
magnetic anisotropy. This material could be interesting for dense data
storage, as well as curvature-induced magnetic phenomena such as the
non-reciprocity of spin-wave propagation.
Flux-closure domains in high aspect ratio electroless-deposited CoNiB nanotubes