Enhanced resonance frequency in Co₂FeAl thin film with different thicknesses grown on flexible graphene substrate

The flexible materials exhibit more favorable properties than most rigid substrates in flexibility, weight saving, mechanical reliability, and excellent environmental toughness. Particularly, flexible graphene film with unique mechanical properties was extensively explored in high frequency devices. Herein, we report the characteristics of structure and magnetic properties at high frequency of Co₂FeAl thin film with different thicknesses grown on flexible graphene substrate at room temperature. The exciting finding for the columnar structure of Co₂FeAl thin film lays the foundation for excellent high frequency property of Co₂FeAl/flexible graphene structure. In-plane magnetic anisotropy field varying with increasing thickness of Co₂FeAl thin film can be obtained by measurement of ferromagnetic resonance, which can be ascribed to the enhancement of crystallinity and the increase of grain size. Meanwhile, the resonance frequency which can be achieved by the measurement of vector network analyzer with the microstrip method increases with increasing thickness of Co₂FeAl thin film. Moreover, in our case with graphene film, the resonance magnetic field is quite stable though folded for twenty cycles, which demonstrates that good flexibility of graphene film and the stability of high frequency magnetic property of Co₂FeAl thin film grown on flexible graphene substrate. These results are promising for the design of microwave devices and wireless communication equipment.