Tuning Magnon-Photon Coupling in a Planar Resonator

• William Neuschwender, Physics, State University of New York at Geneseo

• M. Benjamin Jungfleisch, Physics and Astronomy, University of Delaware

Magnonics, the study of spin waves (magnons) in magnetic materials, holds promise for advancing data storage, processing, and communication technologies. An important aspect of magnonics research is the coupling between magnons and photons, enabling hybrid systems that can leverage the unique properties of both excitations. Dissipative coupling, a type of magnon-photon interaction where energy is exchanged between the two systems without coherent oscillations, is crucial for manipulating and harnessing these interactions in quantum sensing devices. Here, we explore the tuning of magnon-photon coupling within a planar resonator, employing samples of Yttrium Iron Garnet (YIG) spheres and thin films. We utilize microwave spectroscopy to excite and control magnons using planar resonator setup that allows an on-chip integration, which is crucial for developing scalable, miniaturized magnonic devices. By systematically varying the external magnetic field, sample positions, and dimensions of two copper strips (length, width, relative angle), and examining the coupling strength between magnons and photons, we demonstrate control over the interaction dynamics. Our measurements were not able to show dissipative coupling (level attraction) using multiple different planar resonators. What we were able to find was level repulsion (another well established form of magnon-photon coupling) of higher-order magneto-static modes excited at sample positions on the resonator where we expected dissipative coupling to occur. Likewise, we also observed uncoupled higher-order magnetostatic modes at various sample positions. These findings suggest alternative pathways are needed for controlling magnon dynamics and interactions in planar resonator systems. Future considerations into the YIG sample position, resonator design such as the length, width, and angle between the copper strips need to be considered to further probe the efficacy of planar resonators for dissipative coupling applications.