Acoustically Driven Magnon-Phonon Coupling in a Layered Antiferromagnet*

The well-established fabrication of compact surface acoustic wave (SAW) devices, together with well-defined resonance frequencies, places SAWs as an attractive route to manipulate the magnetization states in spintronics, all of which is made possible by the magnetostriction and magnetoelastic effects [1]. In this talk, I will introduce the basic principles of our SAW devices, and our resonant coupling experiments of SAWs with magnetic films. For resonant coupling of SAWs with magnetic films, we interpret the interaction between SAWs and

coherent excitations of magnetization precession or spin waves. More specific to the focus of the session, I will present our recent demonstration of acoustically driven spin-wave resonance in a crystalline antiferromagnet, chromium trichloride, via surface acoustic wave irradiation [2]. The resulting magnon-phonon coupling is found to depend strongly on sample temperature and external magnetic field orientation, and displays a high sensitivity to extremely weak magnetic anisotropy fields in the few mT range. Our work demonstrates a natural

pairing between power-efficient strain-wave technology and the excellent mechanical properties of Van der Waals materials, representing a foothold toward widespread future adoption of dynamic magnetoacoustics.

[1] J. Puebla, Y. Hwang, S. Maekawa, Y. Otani, Appl. Phys. Lett. 120, 220502 (2022)

[2] T.P. Lyons, J. Puebla, K. Yamamoto, R.S. Deacon, Y. Hwang, K. Ishibashi, S. Maekawa, Y. Otani, arXiv preprint arXiv:2303.08305 (2023) To appear in Phys. Rev. Lett.