Paper
Curvilinear magnonic crystal based on 3D hierarchical nanotemplates
Authors
Gianluca Gubbiotti, Olha Bezsmertna, Oleksandr V. Pylypovskyi, Rui Xu, Stephane Chiroli, Fatih Zighem, Claudia Fernandez Gonzalez, Andrea Sorrentino, David Raftrey, Daniel Wolf, Axel Lubk, Peter Fischer, Damien Faurie, Denys Makarov
Abstract
Curvilinear magnetic nanostructures enable control of magnetization dynamics through geometry-induced anisotropy and chiral interactions as well as magnetic field modulation. In this work, we report a curvilinear magnonic crystal based on large-area square arrays of truncated nanospikes fabricated by conformal coating of 3D hierarchical templates with permalloy thin films. Brillouin light scattering spectroscopy reveals anisotropic band structure with multiple dispersive and folded Bloch-type dispersive spin-wave modes as well as non-dispersive modes exhibiting direction-dependent frequency shifts and intensity asymmetries along lattice principal axes. Finite element micromagnetic simulations indicate that curvature-induced variations of the demagnetizing field govern the magnonic response, enabling the identification of modes propagating in nanochannels and other localized on nanospike apexes or along the ridges connecting adjacent nanospikes. The combination of geometric curvature and optical probing asymmetry produces directional dependence of magnonic bands, establishing 3D hierarchical templates as a versatile platform for curvature-engineered magnonics.