Azimuthal Spin Wave Excitations in Magnetic Nanodots over the Soliton Background: Vortex, Bloch and Néel-like skyrmions

Abstract

We study azimuthal spin-wave (SW) excitations in a circular ferromagnetic nanodot in different inhomogeneous, topologically non-trivial magnetization states, specifically, vortex, Bloch-type skyrmion and Néel-type skyrmion states. Continuous mapping of the SW spectrum between these states is realized with gradual change of the out-of-plane magnetic anisotropy and Dzyaloshinskii-Moriya exchange interaction (DMI). Our study shows lifting of the SW frequencies degeneracy and change in systematics of the frequency levels. The change is induced by a geometrical Berry phase, that is present for the dot-edge localized SWs in a vortex state and vanishes in skyrmion states. Furthermore, channeling of the azimuthal SWs localized at the skyrmion edge is present and induces large frequency splitting. This is attributed to DMI induced nonreciprocity, while coupling of the breathing and gyrotropic modes is related to soliton motion. Finally, an efficient coupling of the dynamic magnetization in the skyrmion state to uniform magnetic field in nanodots with non-circular symmetry is shown.

11 pages, 9 figures

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• Effect of Dzyaloshinskii-Moriya interaction on magnetic vortex switching driven by radial spin waves
• Interplay between spin wave and magnetic vortex
• Spin-wave mediated interactions for Majority Computation using Skyrmions and Spin-torque Nano-oscillators
• Stabilization and dynamics of magnetic antivortices in a nanodisk with anisotropic Dzyaloshinskii-Moriya interaction
• From the spin eigenmodes of isolated Néel skyrmions to the magnonic bands of a skyrmionic crystal: a micromagnetic study as a function of the strength of both the interfacial Dzyaloshinskii-Moriya and the exchange constants
• Spin wave frequency hysteresis in Ir/Co/Pt multilayers with Dzyaloshinskii-Moriya interaction
• Field Theory of Linear Spin-Waves in Finite Textured Ferromagnets
• Giant mode splitting of azimuthal spin waves in radial vortices