0_8443 Magnons can not easily be gated or trapped, unlike electrons or photons. Future magnonic devices that mimic established electronics and photonics concepts might benefit from gated magnons, such as quantum point contacts, magnonic crystals, and magnonic quantum bits. One way to trap magnons is physical confinement by producing rectangular or circular YIG structures. However, Qin et al., [1] demonstrated that the local downshift of the spin-wave dispersion relation of YIG film by partially covering it with a ferromagnetic metal acts as a potential barrier where magnons can be partially reflected. As a proof-of-concept, we report magnon confinement in an all-on-chip YIG cavity by partially covering a YIG film with a Permalloy layer.[2] We take advantage of the magnon-magnon coupling in the hybrid YIG/Py bilayer to define on-chip distinct regions where magnons can be partially reflected. We confirm the magnon confinement by measuring multiple spin pumping voltage peaks in an nm-width platinum strip placed along the center of the cavity. Those peaks match multiple backward volume spin wave modes calculated for a YIG cavity with similar geometry dimensions.[3] Modes are not present in a remote Pt strip placed outside the cavity, where the spin pumping volrage has an identical shape compared to the FMR absorption of the YIG film. Multiple peaks are also not present by replacing the magnetic Py film with gold. All the measurements were performed at room temperature. The fabrication of μ-size YIG cavities following this technique may represent a new approach to gate coherent magnons. At the same time, the spin pumping voltage demonstrates to be a trustworthy local nm-sized rf detector.[1] - H. Qin et al., "Nanoscale magnonic fabry-pérot resonator for low-loss spin-wave manipulation", Nature Communications 12, 1–10 (2021).
[2] - O. Alves Santos et al., "All-on-chip magnon confinement using magnon-magnon hybrid system", in preparation (2023).
[3] - A. Mahmoud et al., "Introduction to spin wave computing", Journal of Applied Physics 128, 161101 (2020).