Symmetry and curvature effects on spin waves in vortex-state hexagonal nanotubes

Analytic and numerical studies on curved magnetic nano-objects predict numerous exciting effects that can be referred to as magneto-chiral effects, which do not originate from intrinsic Dzyaloshinskii-Moriya interaction or interface-induced anisotropies. In constrast, these chiral stem isotropic exchange dipole-dipole interaction, present in all materials, acquire asymmetric contributions case of geometry the specimen. As a result, for example, spin-wave dispersion round nanotubes becomes asymmetric, namely spin waves same frequency propagating opposite directions along nanotube exhibit different wavelenghts. Here, using time-resolved scanning transmission X-ray microscopy experiments, standard micromagntic simulations dynamic-matrix approach, we show spectrum undergoes additional drastic changes when transitioning continuous discrete rotational symmetry, i.e. hexagonal nanotubes, are much easier fabricate. The polygonal shape introduces localization modes both sharp, highly corners flat edges. Moreover, due degenerate nature with azimuthal wave vectors known tubes is partly lifted, resulting singlet duplet modes. For comparison our calculate microwave absorption numerically obtained mode profiles shows dedicated antenna design paramount magnonic applications 3D nano-structures. To knowledge first experiments directly showing real space propagation nano objects.