Magnons represent the spin excitations in systems of coupled spins. Direct exchange coupling as well as magnonic spin-currents can result in a coupling of different magnons in all-magnetic heterostructures or even single-phase materials with multiple magnon branches, in particular antiferromagnets.

We use interfacial spin-torques in all-magnetic hybrid thin film structures for the excitation of sub-100nm wavelength magnons from uniform spin dynamics [1]. We showed that ultrastrong exchange-enhanced magnon-magnon coupling arises in compensated ferrimagnets with spin dynamics closely resembling those of antiferromagnets [2]. These concepts are promising for potential magnonic applications.

Moreover, we study spin dynamics in exotic and topologically protected magnetic textures. These textures, so called magnetic skyrmions, are not stabilized by the interaction of external magnetic fields and dipolar coupling, but rather by intrinsic, magnetic-field free antisymmetric three-site quantum-mechanical spin-spin exchange interactions. We find that the magnetic texture arising due to these spin-spin interactions lead to qualitatively new spin dynamical phenomena with great application potential as natural magnonic crystals for data processing [3].

[1]   S. Klingler, V. Amin, S. Geprägs, K. Ganzhorn, H. Maier-Flaig, M. Althammer, H. Huebl, R. Gross, R. D. McMichael, M. D. Stiles, S. T. B. Goennenwein, and M. Weiler, Spin-Torque Excitation of Perpendicular Standing Spin Waves in Coupled YIG/Co Heterostructures, Phys. Rev. Lett. 120, 127201 (2018).

[2]  L. Liensberger, A. Kamra, H. Maier-Flaig, S. Geprägs, A. Erb, S. T. B. Goennenwein, R. Gross, W. Belzig, H. Huebl, and M. Weiler, Exchange-Enhanced Ultrastrong Magnon-Magnon Coupling in a Compensated Ferrimagnet, Phys. Rev. Lett. 123, 117204 (2019).

[3]  M. Weiler, A. Aqeel, M. Mostovoy, A. Leonov, S. Geprägs, R. Gross, H. Huebl, T. T. M. Palstra, and S. T. B. Goennenwein, Helimagnon Resonances in an Intrinsic Chiral Magnonic Crystal, Phys. Rev. Lett. 119, 237204 (2017).