Interface engineering of large-scale and flexible Cu/YIG heterojunctions

With the development of aerospace and modern communication towards portability and miniaturisation, especially in high-frequency microwave devices, developing the large-scale and low-damping flexible ferrite materials is the top priority. Yttrium iron garnet (Y₃Fe₅O₁₂, YIG) is widely used in microwave filters, phase shifters, isolators, etc., being the research hotspot of flexible devices due to high-resistivity, low-damping and good chemical stability. In this paper, large-scale (Diameter 40 mm) and flexible YIG films with damping constant (5 × 10⁻⁴) and inhomogeneous broadening (66.7 Oe) were prepared by double-cavity magnetron sputtering technology. Then, flexible Cu/YIG heterojunctions with different Cu thicknesses were prepared. The change in the ferromagnetic resonance field of the heterojunction during bending does not exceed 3%, which does not exceed 0.3% after stress removal (bending diameter 10 mm). The low-cost and easy to operate process of flexible Cu/YIG heterojunctions, together with excellent bending characteristics, offer tremendous potential applications in next generation flexible electronic devices.