Self-Hybridization and Tunable Magnon-Magnon Interactions in Layered Antiferromagnets
Department of Physics and Astronomy, Wayne State University
Abstract.– Within antiferromagnetic materials and metamaterials, magnons, with frequencies spanning tens of GHz to THz frequencies exist at all wavenumbers. This availability of ultrafast magnons is largely responsible for the magnetism community’s recognition that antiferromagnets should play an active role in next-generation electronics, magnetics, and opto-electronics [1,2]. In this work, we examine, through modeling and experiment, magnons in layered antiferromagnetic materials. Of particular interest are van der Waals magnets, like CrCl3, and synthetic antiferromagnets which have ferro- and antiferromagnetic intra- and interlayer interactions. These materials have recently been shown to have tunable magnon-magnon interactions amongst optical and acoustic magnons that can be controlled via symmetry-breaking external fields or dipolar interactions. In this talk, I will focus on special cases where the number of magnetic layers is greater than two and far from the larger layer limit. Here, magnon-magnon interactions facilitate a “self-hybridization” effect where pairs of optical or acoustic magnon branches can interact, and characteristic avoided energy level crossings can be found in the magnon spectrum . Unlike the previously reported examples, the strength of the magnon-magnon interaction we consider is amenable to electric control via the application of spin-torques on the magnetic surface layers [3,4]. The tailoring of the magnon spectrum, via electrical control, can provide a useful tool in the realization and manipulation of antiferromagnetic-based memories, spin-torque oscillators, and hybrid quantum systems, e.g. magnon-photon-qubits, where antiferromagnetic materials provide the magnonic platform [1,2].
 S.A. Siddiqui, J. Sklenar, K. Kang, M. J. Gilbert, A. Schleife, N. Mason and Axel Hoffmann. Journal of Applied Physics 128, 040904 (2019).
 D. D. Awschalom et al. IEEE Transactions on Quantum Engineering 2, 5500836 (2021).
 J. Sklenar and W. Zhang, Physical Review Applied 15, 044008 (2021).
 T. Jeffrey, W. Zhang, and J. Sklenar, Applied Physics Letters 118, 202401 (2021).
Host: Shulei Zhang