Spin-wave eigenmodes in direct-write 3D nanovolcanoes
Authors: O. V. Dobrovolskiy, N. R. Vovk, A. V. Bondarenko, S. A. Bunyaev, S. Lamb-Camarena, N. Zenbaa, R. Sachser, S. Barth, K. Y. Guslienko, A. V. Chumak, M. Huth, and G. N. Kakazei
Appl. Phys. Lett. 118, 132405 (2021)
Abstract: Extending nanostructures into the third dimension has become a major research avenue in modern magnetism, superconductivity, and
spintronics, because of geometry-, curvature-, and topology-induced phenomena. Here, we introduce Co–Fe nanovolcanoes—nanodisks
overlaid by nanorings—as purpose-engineered 3D architectures for nanomagnonics, fabricated by focused electron beam-induced deposition.
We use both perpendicular spin-wave resonance measurements and micromagnetic simulations to demonstrate that the rings encircling the
volcano craters harbor the highest-frequency eigenmodes, while the lower-frequency eigenmodes are concentrated within the volcano crater,
due to the non-uniformity of the internal magnetic field. By varying the crater diameter, we demonstrate the deliberate tuning of higherfrequency
eigenmodes without affecting the lowest-frequency mode. Thereby, the extension of 2D nanodisks into the third dimension allows
one to engineer their lowest eigenfrequency by using 3D nanovolcanoes with 30% smaller footprints. The presented nanovolcanoes can be
viewed as multi-mode microwave resonators and 3D building blocks for nanomagnonics.