Anatomy of inertial magnons in ferromagnets

Abstract

We analyze dispersion relations of magnons in ferromagnetic nanostructures with uniaxial anisotropy taking into account inertial terms, i.e. magnetic nutation. Inertial effects are parametrized by damping-independent parameter $\beta$, which allows for an unambiguous discrimination of inertial effects from Gilbert damping parameter $\alpha$. The analysis of magnon dispersion relation shows its two branches are modified by the inertial effect, albeit in different ways. The upper nutation branch starts at $\omega =1/\beta$, the lower branch coincides with FMR in the long-wavelength limit and deviates from the zero-inertia parabolic dependence $\simeq {\omega }_{FMR}+D{k}^2$ of the exchange magnon. Taking a realistic experimental geometry of magnetic thin films, nanowires and nanodiscs, magnon eigenfrequencies, eigenvectors and $Q$-factors are found to depend on the shape anisotropy. The possibility of phase-matched magneto-elastic excitation of nutation magnons is discussed and the condition was found to depend on $\beta$, exchange stiffness $D$ and the acoustic velocity.

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• Inertial spin waves in ferromagnets and antiferromagnets
• Theory of inertial spin dynamics in anisotropic ferromagnets
• Influence of inter-sublattice coupling on the terahertz nutation spin dynamics in antiferromagnets
• Hybrid magnon-phonon cavity for large-amplitude terahertz spin-wave excitation
• High dynamic-range quantum sensing of magnons and their dynamics using a superconducting qubit
• Inertial spin waves in spin spirals
• Micromagnetic study of inertial spin waves in ferromagnetic nanodots
• Theory of tensorial magnetic inertia in terahertz spin dynamics
• Dynamically generated spin-interactions and nutational spin inertia in normal metal-ferromagnet heterostructures
• Nonreciprocal inertial spin-wave dynamics in twisted magnetic nanostrips
• Magnetization switching in the inertial regime
• Optically induced magnetic inertia and magnons from non-Markovian extension of the Landau-Lifshitz-Gilbert equation
• Controllable and Non-Dissipative Inertial Dynamics of Skyrmion in a Bosonic Platform