Hybrid systems have attracted considerable attention due to their fundamental significance and potential technological applications in low-loss spin-based information processing and communication. Herein, we investigate temperature-dependent magnon-magnon coupling in a sputtered ${\mathrm{Co}}_{90}{\mathrm{Zr}}_{10}$/${\mathrm{Gd}}_{29}{\mathrm{Fe}}_{51}{\mathrm{Co}}_{20}$ (CoZr/GdFeCo) metallic heterostructure. Broadband ferromagnetic resonance reveals a clear avoided crossing between the uniform ferromagnetic resonance mode of CoZr and the perpendicular standing spin-wave mode of GdFeCo at room temperature. The minimum frequency separation (anticrossing gap) between the two hybridized branches is used to quantify the interlayer magnon-magnon coupling strength. Upon cooling, the coupling strength evolves nonmonotonically and reaches a maximum value of approximately 1 GHz near 200 K, close to the compensation region of GdFeCo. Linewidth analysis of the hybrid modes further reveals a distinct temperature-dependent spin-pumping contribution. The correlation between the linewidth-derived spin-pumping variation and the coupling strength suggests that the interfacial spin pumping, which is sensitive to the compensation behavior of GdFeCo, is involved in the modulation of the mode hybridization. Our experimental results provide insight into the temperature-dependent control of coupled magnon dynamics and suggest a promising route toward thermally responsive integrated magnonic devices.

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• Magnetism
• Magnons
• Spin pumping
• Spin waves
• Bilayer films
• Ferrimagnets
• Heterostructures
• Ferromagnetic resonance
• Landau-Lifschitz-Gilbert equation